Fitting has three outer thread dimensions, ¾ NPT , 13/16-16 and ¾-16UNF. Accepts JÄGER Re-Direct Flash Hiders, JÄGER "Versa-Brake" System, Gestalt Verdampfen Compensator and Ferragane Mini..  Inner dimension of 9/16-24 RH.  Made from hardened carbon steel with Anti-Rust Black Oxide matte finish.  Fits the following platforms*: .40 XD,FN FAL, AR Grendal, Older Mini 14’s, Most Threaded .40 Caliber Pistols, Glock 20 Pistol, MP5 and H&K 94 9mm.   * To ensure proper fit, confirm your rifle's thread dimensions prior to purchase of this part.