The MEPRO 21 reflex sights by Meprolight feature battery-free dual illumination. The large 30mm objective offers an unobstructed view when shooting with both eyes open. The sight is powered by a fiber optic collector in bright conditions and a tritium light source in low-light conditions. The mount allows for fast attachment to rail-equipped firearms. Also designed to work with a red-dot magnifier. Features:Allows the use of iron sights, co-witnessUses no batteriesIllumination is achieved with fiber optic light collection during the day and tritium at nightSuitable for use with all night vision goggles and scopesMount includedWaterproofIncludes neoprene scope cover