There are some Chinese made "Surefire E series" clicky tail caps for sale out there on the net that look a bit like the Defender tail cap. Given the price I took a chance and ordered a couple. Why am I posting here..depending on the E series light you want to put them on, it may be a tail cap in kit form. The clicky switch is secured against a bulkhead from the boot end with the boot retaining ring.
The good news:
The threads are compatible and the thread length and o-ring clearance are OK, at least on my 2 samples
The switch retaining ring is not lock-tited
The bad news:
The switch boot is extra tall, so aftermarket replacements may not work
The spring on the switch could be a little longer, it will barely make contact with the battery
and the biggie...the switch is set up to conduct through the threads of the tail cap to the flashlight body
If you have a bare aluminium flashlight body, it should work fine. (I do, and it did, of course I bought it for another light) But most E series Surefires, Alephs, etc., have anodized threads and rely on the end of the body for the contact to the switch. So you could remove the anodizing from the bulkhead. But after I broke the spring off one of the switches by trying to stretch it out a little, I decided to ream out the bulkhead and extend the 11/16-20 threads up into the switch area and install a McClicky. There's enough wall thickness to get reasonably deep threads and the fix worked well enough that I modified the other tail cap as well.
I did most of the work holding the tail caps in my hand, and even so the "anodizing" shows a few flecks, so i doubt it's going to hold up long term. But as inexpensive E series tail cap hosts, they were worth buying.
The good news:
The threads are compatible and the thread length and o-ring clearance are OK, at least on my 2 samples
The switch retaining ring is not lock-tited
The bad news:
The switch boot is extra tall, so aftermarket replacements may not work
The spring on the switch could be a little longer, it will barely make contact with the battery
and the biggie...the switch is set up to conduct through the threads of the tail cap to the flashlight body
If you have a bare aluminium flashlight body, it should work fine. (I do, and it did, of course I bought it for another light) But most E series Surefires, Alephs, etc., have anodized threads and rely on the end of the body for the contact to the switch. So you could remove the anodizing from the bulkhead. But after I broke the spring off one of the switches by trying to stretch it out a little, I decided to ream out the bulkhead and extend the 11/16-20 threads up into the switch area and install a McClicky. There's enough wall thickness to get reasonably deep threads and the fix worked well enough that I modified the other tail cap as well.
I did most of the work holding the tail caps in my hand, and even so the "anodizing" shows a few flecks, so i doubt it's going to hold up long term. But as inexpensive E series tail cap hosts, they were worth buying.