CRS-2 5.56 NATO Rifle Suppressor with QDC Flash Hider by Knight's Armament. The CRS-2 suppressor was designed to virtually eliminate flash and system backpressure while delivering durability. Pressure Reduction Technology minimizes back pressure, reducing gas in the system that can affect bolt carrier velocity and rate of fire. The Quick Detach Coupling (QDC) ensures minimal and consistent Point of Impact shift and is compatible with 5.56mm QDC muzzle devices. Overall length is 6.26 inches, adds 5.4 inches to the bare muzzle, and weighs 15 oz.