CZ 805 Bren S1 Carbine .223 Remington/5.56mm 16.2 Inch Threaded Barrel 1/2x28 TPI Flip-Up Sights Folding Adjustable Stock Black 30 Round. Equipped with the factory s folding adjustable stock. Chambered in .223/5.56×45 and using the ubiquitous STANAG magazine from the AR15/M16. Easily accepts optics and lights on its top and bottom Picatinny rails. An effective two-port muzzle brake helps keep the Bren solidly on target and reduces recoil and muzzle flip. Aluminum frame. Polymer grips. Flip-up sights (2 rear aperture sizes). Cold hammer forged barrel with threaded muzzle (1/2x28 TPI). Ambidextrous thumb safety.