The smallest of EOTech's offerings, the XPS2-2 comes in at 9oz. The XPS2-2 is a great offering for military and law enforcement. The 600 hours of run time comes by way of a single 123 battery. The XPS2-2 small size leaves more than enough room for back up iron sights or a magnifier. Mounts to 1" Weaver Picatanny (1913) rail. Not compatible with night vision.