Really oddity.....Unless exposure light can recognise them battery:D
It's a normal phenomenon that same model batteries length and diameter has 1-2mm fluctuation, with/without PCB, different outside tube material.
Most common wavelength of UV LED is 365nm and 395nm, but the price is variety from $-$$$ according to it performance and place of origin. The most expensive UV I've used is about $150 for one LED. It's a customs light for underwater photography lighting.
Ps. 365nm is 5W, 395nm is 3W.
+2 Let your friends know CPF and faimilar with flashlight, it will have more fun that exchange thought with them. Or not, they manybe only think "why you are intoxicated by those similar flashlights?", like man can't understand the difference between ladies lipstick. ;)
Re: Knife & Light pics. (Identify your images!)
Stop said how bright your light is, and talking with them about your flashlight's appearance,application or different led colors.:naughty:
Thoughts from a girl~~~