Figured I would make a quick post here about my 501B flashlight host that houses a 445nm laser diode module with a new key switch mod I took on for a client who was interested in buying this setup. I did lots of searching online for some key switch that would be proper size for this mod, after some quick measurements with a caliper I set off to Google and finally came across these electronic key switch on eBay.
They arrived promptly from the US Shipper, and I took apart the tail-cap on the 501B; It was very simple to convert this key-switch to my host by cutting the heatshrink off, and de-soldering the wiring from the pins. I then bent the outer pin over to touch the tailcap housing, and the middle pin bends over onto a black tab that sticks up in the middle of the key-switch body. Perfect, no spring required (although optional) and it functions better then the C6 and 501B factory tail-switch in my opinion! Enjoy!