Engineered to perfection and built for performance, the Heresy DesignA(R) 16.3" AUGA(R) owners to easily switch calibers and shoot suppressed, even with subsonic ammunition, with minimal gas blowback. Ships with a barrel assembly. FEATURES 5/8x24 Threaded Barrel Compatible with Standard and NATO stocks Easy Install without Modification Upgraded Gas Piston System Pistol Length Gas Port for Subsonic Operation Suppressor Ready 3-Setting Adjustable Gas System Anodized Aluminum Quad Rails with Heat Isolators Isonite coated wear parts Limited Lifetime Warranty Not compatible with Steyr AUGA3 SA Models Mfg: Heresy Design Inc.