Yankee Hill Machine sRx Muzzle Brake 4405MB28. QD long brake designed for hub system with sRx adapters. Thread pattern 1/2-28 tpi, steel construction, phosphate finish. OAL 2.30", diameter 9.375". Compatible with sRx adapters (YHM-4400). Mfg Part Number 4405MB28; UPC 841812101529. Manufactured by Yankee Hill Machine.