The Accuracy Systems Harmonic Stabilizer with Adjustable Gas Block allows you to tune your gas system for optimum performance. By adjusting the gas system you can; adjust ejection distance of the brass and increase recovery, reduce wear on your operating rod and increase accuracy by tuning the harmonics of your rifle. The gas block can also be turned off completely so the rifle will operate as a single shot. Easy installation, replaces the factory gas block with four screws. This gas block fits 0.625" diameter barrels. Kit Includes: Harmonic StabilizerGas Pressure Adjustment ScrewBarrel ClampGas PipeTop & Bottom of Gas BlockSwivel Stud4 screwsAdjustment Allen WrenchesInstructions FeaturesStabilizing bar screws directly into the face of the gas block giving you a more rigid, more stable integrated connectionHole pattern matches Ruger's factory Gas block Top & Bottom for after market add on accessories Gas Pressure Front Adjustment screw is in a covenant location for easy reach ...