The Aimpoint PRO is parallax-free, non-magnifying red dot sight is ready at all times, with no switches or levers to fumble with. Simply install the supplied battery, turn the Aimpoint PRO on, and forget about it - for up to 3 years! 2 MOA center-dot, with 6 daylight and 4 night vision brightness settings, enables accurate target engagement under a broad variety of conditions. Includes a detachable spacer that allows co-witnessing with the standard iron sights on AR-15/M16/M4 weapons. Or remove the spacer to install the Aimpoint PRO on shotguns or submachine guns. Integrated "rail-grabber" mount with knurled, oversized knob aids in quick attach/detach on Picatinny ra Mfg: Aimpoint