Blitzkrieg Components AR 9mm Heavy Damped Buffer RB5015HD. A 9mm hydraulic buffer designed for AR-15 PCC builds and short-stroke systems. Features stiff hydraulic dampening and a heavier return spring for high-stress applications. Length 3.9 inches, diameter 0.76 inches, weight 6 oz. Machined from 17-4 stainless steel with a stainless finish. Gas system: Blowback. Made for AR-9 platforms in USA. Not recommended for short barreled builds. Stops just behind the bolt catch to optimize cycling. Includes Blitzkrieg Components 9mm Heavy Damped Buffer. Compatible with AR-9 configurations.