The XPS3 is smaller and lighter than all other holographic weapon sights but just as fast. Law enforcement officers and hunters appreciate the light weight and compact size for carrying convenience on the job and in the woods. The XPS3 runs on a single 123 battery. The single-lithium-battery configuration allows more rail space, leaving more room for rear-iron sights, magnifiers, or a night vision mount. Features : Water Resistant Fits weaver or MIL-STD-1913 rail 20 daylight settings 10 additional settings for Gen I through III+ night vision devices