Fostech Throttle Adjustable Gas Block Stainless Steel 0.625. This is particularly useful for managing excess gas to reduce blowback on suppressed firearms or competition builds where the shooter is looking to mitigate recoil. Specifications for Fostech Throttle Adjustable Gas Block: Manufacturer: Fostech Color: Stainless Steel Fabric/Material: Stainless Steel Package Contents: Fostech Throttle Adjustable Gas Block Fostech 2507-SS-625: Throttle Adjustable Gas Block Stainless Steel 0.625