Heat-Hardened 7075 AL Construction 3-Thread Adaptor. Black Anodized Finish. Fits 0.92 Inch Diameter Ruger 10/22 Bull Barrels. 3 thread dimensions in one fitting: ¾ NPT, 13/16-16 and ¾-16UNF. Connects to barrel with nylon-tipped stainless steel set screws. No machining required to attach this part.