Aside from taking a good beating and still working afterwards. Handgun lights usually have a mounting system built into the light so it can attach to the rail of the weapon. There are some mounts you can buy to attach to your weapon that will hold a light depending on the dia. of the tube. A lot of lights made for rifles come with mounting hardware, whether it be Mlock, a Pic/Weaver, or an old 3/8 dovetail on some 22lr guns.
Most of them are just normal flashlights using normal cells and emitters. Of course most of the good ones are potted and extra material added where needed to hold up to whatever round will be fired from the weapon. Though a few of the more well known brands most gun people know still use out dated emitters and are 5 times the price they actually should be. Just think $200 200lumen lights. I won’t mention any names.
