SPECS: 4140 steel, black oxide finish, matte black. .223 - 23⁄8" (6cm) long, .859" (2.2cm) O.D. 3.2 oz. (90g) weight. ½"-28 tpi RH thread. Fits .223/5.56 NATO AR-15-type rifles and carbines. .308 - 2½" (6.3cm) long, .903" (23mm) O.D. 3.3 oz. (94g) weight. 5⁄8"-24 tpi RH thread. Fits AR-style rifles chambered in .308/7.62mm.