# ReviewTheLight: Acebeam K40M (3000 Lumen MT-G2 + Control Ring)



## Bigmac_79 (Sep 2, 2014)

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Supbeam recently upgraded their name to Acebeam, and consequently have upgraded a few of their models. The K40 has been upgraded from an XM-L to the MT-G2 emitter, a larger and brighter (though slightly less efficient) emitter, and renamed the K40M. It still includes the large reflector for long throw, and the control ring user interface. Presenting the Acebeam K40M:



_
Thanks to Acebeam for providing the K40M for review._

I’ll be reviewing the K40M in two sections: first, I’ll discuss the light objectively (the facts about the light itself), then I’ll discuss the light subjectively (my impressions about the light's performance when used for specific applications). If you have any other specific applications you'd like the light tested for, let me know and I'll see what I can do.

Video Review

Below is a video review of the K40M. Due to my old image hosting site closing down, I've got new restrictions on image uploads and have replaced the "Construction" section of my reviews with a more detailed video review.


_This video is available in 1080p HD, but defaults to a lower quality. To select the playback quality click the settings button (looks like a gear) after you've started the video._


Objective

*Manufacturer's Specifications*

Price: 120 USD





Product Manual







Dimensions





Plus, here's a few shots with some good detail.


































*User Interface*

The K40M has six brightness levels, a Standby mode, and a Strobe mode, controlled by the rear tail switch and the control ring.

To turn the light on and off, click the rear tail switch. To choose the mode, rotate the ring to the desired mode position. An arrow on the ring indicates the mode chosen. From left to right (with the light pointing away form you), the modes are Level 1 - Level 2 - Level 3 - Level 4 - Level 5 - Level 6 - Standby - Strobe, with Level 1 being the dimmest and Level 6 being the brightest. Each position on the ring has a detent so that the ring "clicks" into position, and is unlikely to be moved by accident.


*Action Shots*

You can click on any of these shots to see them full size.

Light in Hand








MugShot






BeamSlice




White Wall
_ISO 100, f/3.5, 1/20" 
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Indoor Shots
_ISO 100, f/3.5, 1"
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Outdoor Shots
_ISO 100, f/3.5, 2.5"
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Long-Range Shots
_ISO 100, f/3.5, 15"
_



Fun Shots 








*Performance*

Submersion: I submersed the K40M under a foot of water for about an hour, clicking the switch and turning the ring several times. I found no evidence of water entering or damaging the light.

Heat: The K40M heats up in just a few minutes on Level 6, and the batteries can get hot as well, so I recommend using the highest level for short intervals.

PWM: I detect no pulse-width modulation on any mode of the K40M.

Drop: I dropped the K40M from about a meter onto various surfaces (including grass, carpet, dirt, and hard wood), and found no cosmetic or functional damage.

Reverse Polarity Protection: 

Over-Discharge Protection: The K40M begins to flash intermittently when the batteries get low, so that's your warning that to change or charge them.


Spectral Analysis




All light that we see as white is actually made up of several different colors put together. The relative intensities of the different colors in the mix are what determine the tint of the white we see. For example, cool white LED's have a lot of blue, and warm white LED's have more red or yellow. This measurement was done on a home made spectrometer. The plot below the picture is corrected for the spectral sensitivity of the human eye. Note: the peak in the 900nm region doesn't really exist, it's a piece of the second-order spectrum that's showing up here because of the high intensity of the light source. 

Output and Runtime




ANSI FL-1 runtime ratings are the time it takes for a light to fall to 10% of it's original output (counting from 30 seconds after turning the light on). 

The vertical axis of the graphs below represents a relative brightness measurement using a home made light box. The horizontal axis is time in hours:minutes:seconds. Runtimes are stated in hours:minutes:seconds. These graphs may be truncated to show detail.

*Mode Comparison*

Level 6




Level 5




Level 4





Throwing Distance

ANSI FL-1 standard for stating a light's throwing distance is the distance at which the peak beam intensity (usually at the center of the beam) is 0.25 lux. I calculate throwing distance and candela (lux at 1 meter) by measuring peak beam intensity at five different distances and using the formula lux*distance^2=constant.







Subjective Review

Quick break down:

+ One minute of crazy bright 
+ Sub-lumen low mode
+ Excellent output range, six levels
+ Control ring UI
+ Firm detents in ring
+ Good grip on ring
+ Perfect regulation :twothumbs on all modes!
+ Long throw
+ Beautiful warm tint

- Big
- Battery carrier instead of solid body
- No cutouts in tail rim

When I received the K40M from Acebeam, a little known company previously known as Supbeam (and I think spending a little time going by MicroBlueBear), I was expecting a pretty middle-of-the-road light that would have mediocre construction and little or no regulation. Instead, I get the K40M, a well constructed beast that has an excellent interface and even better performance. I'm very impressed with this light .

Let's start with the output. It claims 3000 lumens, and it just barely touches that point on startup, but can't quite hold it for the ANSI spec 30 seconds, so I rate it at just shy of 2900 at the 30 second mark. That's still very impressive, and I was surprised to see it from this less known company. It keeps this output level for a couple minutes, then drops to hover around 2500-2600, and maintains that solidly for the rest of the run. When the battery begins to get low, the K40M will start to give some flashes periodically as a warning. Then, there is a sharp drop to a very low output (near 0) that's just enough to get around in total dark and find replacement batteries or another light. Every mode behaves this way, except that the lower modes don't have the initial drop that Level 6 does. In my opinion, this is the perfect output pattern--holding the initial output for the entire run, until the very end when they give the warning blinks then drop to the very dim output for a while. In addition to the perfect regulation, the K40M has an excellent output range. It's six output levels cover a range from 3000 lumens all the way down to 0.9 lumens, which is one of the most impressive ranges I've seen in a single light. I think most multi-cell lights like this one go with the idea that if you're carrying something this huge, you're probably not trying to read a book in bed. Generally, it's true, if I'm carrying a light this size I've got something smaller in my pocket to handle low-illumination jobs, but I have to say it's really nice to have the ability to have a super-low all the way up to a super-high on the same light. I find it useful to set to Level 1 and tailstand the light in the middle of a small room, and it can give just enough illumination make the room visible. Also, I appreciate that I don't have to switch the light I'm using if I need to go from a very low to very high output quickly. Particularly, if I'm doing a task that requires very little light I can use the Level 1 and preserve night vision, but have quick access to up to 3000 lumens if I need it quickly. Finally, having three 3100mAh batteries driving a sub-lumen mode means some pretty long runtimes. Acebeam's claim of 1000 hours on Level 1 (I didn't test this ) is about 42 days, which isn't particularly efficient, but still very nice to have available if you need it.

Ok, enough about the output. Next, the control ring. If you've read my reviews before, you'll know I'm a sucker for control rings, because they're the best thing to happen to flashlights since the p-n junction. In summary, it's the most intuitive and simple user-interface I've ever used--you can increase brightness when you want more light, or decrease brightness when you need less light, and never have to move through modes too bright or too dim to get where you want. So, you're not left in the dark for moments when trying to access a high mode or blinded when trying to access a low mode. If you've never used a control ring light, you're in for a treat. If you have used a control ring light and you disagree with me, you're free to go write your own review . Anyway, the control ring on the K40M is very well implemented. They basically come in two flavors, the infinitely variable and the preset modes. The K40M has preset modes, and solid detents that "click" the ring into position and hold it from shifting to some other mode when you're not turning it on purpose. In addition, the control ring on the K40M has some good grooves cut into it, which means you'll be able to get a grip on it even when your hands are a bit cold or wet. The choice of preset modes means you obviously don't have as many output choices as on an infinitely variable ring, but the advantage is that you can memorize the output levels available and their runtimes, and don't have to guess how much time you have, plus they're generally a bit more efficient than the infinitely variable variety.

Next, let's hit a few on the K40M's negatives. First, it's big. No helping that, if you want high output, long throw, and decent runtimes, you'll need a big light, until we have more hi-tech available. The control ring makes the K40M a bit bigger than other lights with similar output and throw, but I consider it certainly worth it. After all, if you're carrying a light this big, a bit of extra volume and weight isn't going to make too much difference in most situations. Second, it has a battery carrier. This is a bit nitpicky, but I do prefer when multi-cell lights have a solid body with slots drilled out for the batteries, vs a removable battery carrier. The solid body design is heavier, but it is better at soaking up heat and is more sturdy than a battery carrier. Again, I tend not to mind some extra weight, so I prefer the solid body design over the battery carrier. Finally, I think the tail section could be improved with some cutouts in the rim around the button. The ring extends beyond the rubber switch cover, which I really appreciate because it gives the solid tailstand ability, but it also makes it a bit harder to reach your thumb around there to hit the switch on such a large light. A few cutouts in that raised section would make reaching the tail switch a bit more comfortable. 

A few more points to cover before we're done. First, this thing can throw. A large emitter like the MT-G2 can handle higher output than something like an XM-L2, but with a larger emitter size, it takes a larger reflector to get the same focus on the beam. The K40M's reflector is plenty large to get that good focus on the beam. There are certainly lights out there that can throw farther, but the K40M runs with the big dogs when it comes to throw. In addition, the beam is a very pleasant warm tint. MT-G2 emitters only come in the 5000 to 2700K range, which is what most people would call neutral to warm white, and I'd say this beam looks around 3500 - 4000K (see the spectral analysis for a quantitative comparison to other lights). Most high-output lights that go with XM-L emitters generally choose cool white tints to get maximum output, so that means the MT-G2 emitter lights stand out with their warmer beams. Generally, warm tints have the advantage of showing colors more accurately and giving better contrast, especially in outdoor environments. 

Overall, I've been very impressed with Acebeam's K40M, and with the high quality I've seen here I'm looking forward to seeing what else Acebeam can do. The K40M is an excellent high output thrower, one of few sporting a control ring interface, and is priced very competitively. If you're looking for a thrower and like the control ring UI, the K40M would be a great choice.


*Long Term Impressions*
I'll fill this part in after carrying the light for a while. If nothing get's added here, either I find nothing else worth noting about the light, or I end up not using it often.


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## joshjp (Sep 3, 2014)

Thanks for this review, were can i buy this light?, also it seems like its compareably to the ThruNite TN35.


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## Bigmac_79 (Sep 3, 2014)

joshjp said:


> Thanks for this review, were can i buy this light?, also it seems like its compareably to the ThruNite TN35.



On Acebeam's website they have a "submit order inquiry" button on the K40M product page. I also see it listed on banggood and ebay for about 120 USD. I don't know if it will become available from other retailers, but it might (it just recently was released).


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## blackFFM (Sep 3, 2014)

Thanks for the review. I like your graphs. I scored one from BG for 95$


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## Bigmac_79 (Sep 3, 2014)

blackFFM said:


> Thanks for the review. I like your graphs. I scored one from BG for 95$



Nice! Did you have some sort of coupon code? I thought I saw them listed for 120.


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## phantom23 (Sep 3, 2014)

About a month ago the price was lower (still under Supbeam brand), and there's still a coupon that currently drops the price down to ~$110.

PS. I got mine as well, it's crazy bright, makes my Xtar Howitzer (which is much bigger) look dim... But it's also pretty big, I have small hands and I can't cross or even touch my fingers with my thumb.


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## Bigmac_79 (Sep 3, 2014)

phantom23 said:


> About a month ago the price was lower (still under Supbeam brand), and there's still a coupon that currently drops the price down to ~$110.
> 
> PS. I got mine as well, it's crazy bright, makes my Xtar Howitzer (which is much bigger) look dim... But it's also pretty big, I have small hands and I can't cross or even touch my fingers with my thumb.



It certainly is big, but I have big hands so it feels pretty comfortable for me. Is one-handed operation of the control ring difficult at all for you?


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## joshjp (Sep 3, 2014)

Bigmac_79 said:


> On Acebeam's website they have a "submit order inquiry" button on the K40M product page. I also see it listed on banggood and ebay for about 120 USD. I don't know if it will become available from other retailers, but it might (it just recently was released).


TY, can i trust banggood? This seems like a steal at $120.


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## phantom23 (Sep 3, 2014)

Yes, you can. I bough mine from them.


Bigmac_79 said:


> It certainly is big, but I have big hands so it feels pretty comfortable for me. Is one-handed operation of the control ring difficult at all for you?


Actually one handed operation is not a problem although control ring is a little bit stiff.


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## Bigmac_79 (Sep 3, 2014)

phantom23 said:


> Yes, you can. I bough mine from them.
> 
> Actually one handed operation is not a problem although control ring is a little bit stiff.



Glad to hear it! The control ring on my review sample, I wouldn't call it stiff, but the detents are substantial, so that it requires some force to get it up and out, but the space in between the detents is smooth.


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## Bigmac_79 (Sep 3, 2014)

joshjp said:


> TY, can i trust banggood? This seems like a steal at $120.



I'm amused that we're carrying this conversation both here and on youtube . Like I said there, I haven't ordered anything from banggood myself, but I know several others have successfully. I'd suggest running a search here on cpf for banggood and scanning through everyone's experiences.


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## joshjp (Sep 3, 2014)

I'm sorry about that, I JUST NOW figured how to type on here with my phone, as before it wouldn't let me type, I will now have to order from banggood, I was gonna get the Olight SR Mini, but this is cheaper and seems better, although that should be much floodier. Thanks again for the review♿


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## phantom23 (Sep 3, 2014)

Shipping from BG is fairly slow but that's not exactly their fault - China Post is quite slow overall. 


Bigmac_79 said:


> Glad to hear it! The control ring on my review sample, I wouldn't call it stiff, but the detents are substantial, so that it requires some force to get it up and out, but the space in between the detents is smooth.


It is smooth indeed but there's more resistance than in other control rings (and I have/had quite a few).


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## avion (Sep 3, 2014)

Thanks, nice review and very interesting flashlight.

ciao


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## Bigmac_79 (Sep 3, 2014)

joshjp said:


> I'm sorry about that, I JUST NOW figured how to type on here with my phone, as before it wouldn't let me type, I will now have to order from banggood, I was gonna get the Olight SR Mini, but this is cheaper and seems better, although that should be much floodier. Thanks again for the review♿



No worries . Yeah, the K40M is going to have more throw, and I really love the control ring interface. The SR Mini is floodier, and a lot more compact.


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## Bigmac_79 (Sep 3, 2014)

phantom23 said:


> Shipping from BG is fairly slow but that's not exactly their fault - China Post is quite slow overall.
> 
> It is smooth indeed but there's more resistance than in other control rings (and I have/had quite a few).



Yes, definitely more resistance than other control rings. Thankfully there is good grip on the ring.


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## Bigmac_79 (Sep 3, 2014)

avion said:


> Thanks, nice review and very interesting flashlight.
> 
> ciao



Glad you like the review 

:welcome:


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## Ernst from Germany (Sep 7, 2014)

Thanks for the Review! It seems so that the Beam is a good compromise between Flood and Throw. Is my opinion right?
Ernst from Germany


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## Bigmac_79 (Sep 7, 2014)

Ernst from Germany said:


> Thanks for the Review! It seems so that the Beam is a good compromise between Flood and Throw. Is my opinion right?
> Ernst from Germany



Hi Ernst! The K40M does have a lot of flood light in it's spill region, but the hotspot is so bright, I'd classify it pretty definitely as a thrower.


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## Danielsan (Sep 8, 2014)

To start from max is a bit stupid in my mind, whoever decided this, it was was a bad decision. That basically means when you need firefly you will be get blinded by 3000lumen first?


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## Bigmac_79 (Sep 8, 2014)

Danielsan said:


> To start from max is a bit stupid in my mind, whoever decided this, it was was a bad decision. That basically means when you need firefly you will be get blinded by 3000lumen first?



Not necessarily--this is a control ring light, so you can turn it to any output level you want, then turn it on. If you don't want to be blinded, just turn the ring to firefly before you turn on the light.


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## Bigmac_79 (Sep 8, 2014)

This review is complete


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## Danielsan (Sep 8, 2014)

Bigmac_79 said:


> Not necessarily--this is a control ring light, so you can turn it to any output level you want, then turn it on. If you don't want to be blinded, just turn the ring to firefly before you turn on the light.



Sorry, i thought this light has no tail switch, then its indeed no problem


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## Bigmac_79 (Sep 8, 2014)

Danielsan said:


> Sorry, i thought this light has no tail switch, then its indeed no problem



No worries


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## joshjp (Sep 13, 2014)

Just ordered this beast, i cant wait.


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## prototype_uk (Sep 17, 2014)

How would this light compare to the Eagletac MX25L3 MT-G2 or the SX25L3? I can't decide if I should purchase this light or a Eagletac


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## phantom23 (Sep 17, 2014)

K40M is bigger and throwier than both, probably not brighter. UI is much better, quality is top notch and it's significantly cheaper.


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## BanditoPete (Sep 17, 2014)

Been looking at this for a while now and thanks for the review. My next thrower too!


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## Bigmac_79 (Sep 18, 2014)

prototype_uk said:


> How would this light compare to the Eagletac MX25L3 MT-G2 or the SX25L3? I can't decide if I should purchase this light or a Eagletac



Sorry, I don't have either of those so I can't weigh in on that.



phantom23 said:


> K40M is bigger and throwier than both, probably not brighter. UI is much better, quality is top notch and it's significantly cheaper.



Thanks for chiming in phantom!


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## Bigmac_79 (Sep 18, 2014)

BanditoPete said:


> Been looking at this for a while now and thanks for the review. My next thrower too!



Glad the review was helpful!


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## joshjp (Sep 27, 2014)

I FINALLY got my K40M today, but i noticed that the hotspot has a lot of artifacts in the beam,is this normal for this light? It looks like the center of the hotspot is grean and theres white swirls around it, i made a video of it and will uploead to Youtube in a bit, i realy hope its supposed to be like that, my Olight M22 Warrier has the same thing to.


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## joshjp (Sep 27, 2014)




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## Bigmac_79 (Sep 27, 2014)

Hey joshjp! It's hard to tell for sure from your video, but I don't see anything that I'd be concerned about from 3 ft away. Being more of a thrower, Acebeam kept the reflector smooth on the K40M, vs a textured reflector. A smooth reflector is going to have some artifacts similar to that, especially a large reflector at a short distance. At longer distances I'm guessing those won't be noticeable. A textured reflector like you see in floodier lights would smooth out the beam a lot to eliminate artifacts like that, but it also would decrease the throwing distance. I don't have any shots at 3ft, but if you take a close look at some of the beamshots in the review (click on them if you can't see them right now, I think I went over my bandwidth cap for my image host) you'll see a few small artifacts in my beam as well.


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## joshjp (Sep 27, 2014)

Im gonna go test it out in a bit, itss my favorite time (night time), i will report back later.


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## Bigmac_79 (Sep 27, 2014)

joshjp said:


> Im gonna go test it out in a bit, itss my favorite time (night time), i will report back later.



Great, I'll look forward to hearing how it goes!


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## joshjp (Sep 27, 2014)

Bigmac_79 said:


> Great, I'll look forward to hearing how it goes!


Just got back, well at 30 or so feet i cqn see it in short grass, but in the long grass i really cant, and at a couple hundred feet i cant, mayby ill get it modded by Vinh and it will mostly go away as it bothers me.


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## mvyrmnd (Sep 28, 2014)

Can anyone compare this to the Solarforce s2200?


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## Ernst from Germany (Sep 28, 2014)

My Acebeam K40 m with SMO Reflektor will arrive Thursday this week. Another member of the TLF i think will test his Lamp in a comparision.
That it is for the moment, but the Fenix LD 60 and the Lumintop PS03 are waiting in the background.


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## toysareforboys (Nov 1, 2014)

I got an e-mail from wallbuys that they are selling for $79, sounds like smokin deal  http://wallbuys.com/instantkill/AceBeam_K40M__1_CREE_MT_G2_Q0_White_3000lm_Flashlight___Black-22492


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## Alex1234 (Nov 1, 2014)

Figure i just throw this in here the k40mvn my vinh the modded verion with higher output and improved heat sinking gets 105,000cd with dome on and over 200cd with domes off(same throw as sr52vn but with a hotspot 3 times the size) thats another option


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## sbrom (Nov 2, 2014)

toysareforboys said:


> I got an e-mail from wallbuys that they are selling for $79, sounds like smokin deal  http://wallbuys.com/instantkill/AceBeam_K40M__1_CREE_MT_G2_Q0_White_3000lm_Flashlight___Black-22492



Thanks for that info & link! I grabbed one at the $79 price, it was some "Instant Kill" sale, and now it says "sold out".


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## markr6 (Jun 25, 2015)

I'm really considering one of these, only if I can get a killer deal.

When I view it on Banggood, it says $84.99. But the page is sort of frozen for about 45 seconds, almost like something is loading. After that, it jumps up to $129.30.


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## Milw light (Feb 14, 2016)

Great review BigMac, any idea the battery voltage when the light starts low voltage flashing?


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## Swedpat (Feb 14, 2016)

This light seems to be very much the same as Thrunite TN35. There are some similarities so close so I wonder if it's the same manufacturer? Anyway I like TN35 so much I consider to get another. And if it will not be available anymore maybe K40M still is.


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## Milw light (Feb 15, 2016)

Swedpat said:


> This light seems to be very much the same as Thrunite TN35. There are some similarities so close so I wonder if it's the same manufacturer? Anyway I like TN35 so much I consider to get another. And if it will not be available anymore maybe K40M still is.


 I just ordered a K40M & the TN35 is available all over in the states. The M is driven harder with a different dedicated reflector. That said Thrunite quality on these lights is second to none as I've read.


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## Theodore41 (Mar 9, 2016)

Hi.
I think that there is a K40S one,that is more of a thrower.

Acebeam
K40S Flashlight Searchlight

Black Body
1500 Lumens
CREE XPL HI Throw 1030M​ Specifications:
LED: Cree XPL HI LED with a lifespan of 10+ years of run time
Max 1500lumens output (3x 18650 batteries)
Output (select by magnetic ring):  Level 1 : 0.9lm(1000hrs);
 Level 2 : 42lm(70hrs);
 Level 3 : 430lm(11hrs);
 Level 4 : 600lm(4.5hrs);
 Level 5 : 950lm(1.5hrs)
 Level 6 : 1500lm(0.9hrs);
 Standby : 65uA
 Strobe : 1500lm;
Working voltage: 4V - 13V;
Max Runtime: 1000 hours;
Max beam distance: 1030meters;
Peak beam intensity: 265000cd;
Impact resistant: 1.2meters;
Waterproof : IPX-8 Standard;
Size: 186mm(length) x 76.2mm(head diameter)*49mm(tube diameter);
Weight: 700.8g(without batteries);
Aircraft grade aluminum body structure;
Premium type III hard anodized anti-reflective coating;

​ 
 
Is there a review of it here please?


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## Lexel (Feb 9, 2019)

I have modded a TN31 to XHP50.2, but the driver seems to have some Output voltage safety feature and does not power up
The drivers are identical in size and control ring just power different LEDs TN31 was XML2

I need to change very likely only one voltage divider

So I would need a high res picture of this driver so I can read all resistor values


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