Trijicon ACOG 3.5x35 Riflescopes BATTERY-FREE ILLUMINATION: Features a tritium/fiber optic illuminated reticle that automatically adjusts the brightness based on available light RUGGED ALUMINUM-ALLOY HOUSING: Forged 7075-T6 aircraft-aluminum-alloy housing provides for a nearly indestructible sighting system BOTH EYES OPEN DESIGN: The ACOG can be used as a CQB sight when shooting both eyes open, utilizing the Bindon Aiming Concept COMBAT PROVEN: No other magnifed optic has been used more in combat than the ACOG BULLET DROP COMPENSATING & RANGING RETICLE: The red triangle ranging reticle allows for bullet drop compensation out to 800 meters for 5.56 (.223 cal)