The Rubber City Armory Adjustable Gas Key enhances performance of low mass and standard mass GI systems without unnecessary disassembly. Gas flow is adjusted and maintained at the carrier with 2 set screws, one to adjust gas flow and one to lock it in place. Made from Pre-Hardened 4140: 28-32RC with radiused corners reducing sharp edges. 2 mounting bolts included. Mfg: Rubber City Armory SPECS: Made from Pre-Hardened 4140: 28-32RC.