Fits JÄGER PMC and other Re-Direct Flash Hiders.  Hardened 7075AL Construction 3-Thread Adaptor. Fits Ruger Mark III .22 Pistol .89" Diameter 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.