Made from 17-4 Stainless Steel and is heat treated then black nitride is finished for improved wear and corrosion resistance. This accessory is for use on fixed barrel systems. – WARNING – NOT FOR USE ON UNLOCKING OR RECIPROCATING BARRELS AS IT MAY CAUSE DAMAGE TO THE SUPPRESSOR – Features: – Interchangeable with suppressors that have 1.125×28 threads – Interchangeable between RAD 9 and 45 – Wrench flats