This gas block is made for standard AR15 barrel diameter 0.750 inch. Port holes are compatible with all standard gas tubes so It can bi installed from pistol length to rifle length. Made from hard and resistant steel EU-42CrMo4. (USA-4140). It is same steel that most barrels are made of. Since almost all factory AR15 are over-gased it’s necessary to reduce amount of gases to reduce recoil and improve target control specially for fast follow up shots. Shooter can adjust how much gases travels to bolt carrier with included long hex hey. This key allows you to adjusted gas block even with hand-guard mounted. Clear and crisp clicks hold the position so there is no need for counter screw. Gas block can easily be disassembled for cleaning and assembled in same position by counting clicks. Advantage with clickable system is that you don’t need counter screw and when you disassemble and clean your gun you simply fully tighten gas block and count clicks (8 clicks) and when you assemble it back you fully tighten and unscrew 8 clicks.