ACOG models are battery free, featuring a tritium/fiber optic illuminated reticle that automatically adjusts the brightness based on available light; Fixed-power design allows for minimal moving parts to create a nearly indestructible sighting system; “Both eyes open” shooting using Trijicon’sBindon Aiming Concept (BAC) feature allows for improved situational awareness; Outstanding Clarity; Bullet drop compensating and target-ranging reticle; Combat Proven; Shock-Resistant; Waterproof