Designed to the exact specifications of the US Special Operations Command for use by elite US forces, the Trijicon ACOG TA01-M4A1. The ranging reticle allows for bullet drop compensation out to 600 meters without any manual adjustments. The reticle will appear black during the daytime and will glow amber in the dark, thanks to Trijicon's patented tritium illumination. Includes backup Iron Sights. No batteries needed! FeaturesAlways On with Tritium Illumination"Both Eyes Open Design"Shock Resistant up to 50 BMGRugged Housing