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: M14.5x1 LH. Made from 7075 hardened AL. Fits the following platforms*:H&K .40