4140 Heat Treated Barrel Nut; Barrel Nut and Wrench Included; Features Patented 4140 Heat Treated Torque Plate; 11.8 oz Installed Weight; 6061 Aluminum Type 3 Hard Coat Anodized; High Quality MIL-STD 1913 Picatinny rails, T-marked for accessory location; Provides continuous monolithic look with full length upper rail; Two Integral Anti-Rotation QD Sling Sockets; 2.43" Tall, 2.15" Wide; 1.3" Inside Diameter