The revolutionary RIFLESPEED(TM) Gas Control System (US Patent #US20200116446A1, additional patents issued and pending) makes controlling your rifle's gas flow reliable, repeatable, and foolproof. Need more gas? Turn it up. Need less gas? Turn it down. With the easy-to-grasp Control Knob, it's that simple and no tools are required. The highly visible numbering on the Control Knob ensures that you'll always know your setting. Return to a previous setting instantly by simply turning the Control Knob. Each setting is indicated by a highly tactile ""click"" for use during times of reduced visibility. Two separate rotation ranges with numbered settings 1-12 a Mfg: Riflespeed