Kaw Valley Precision's adjustable low profile gas blocks are designed with the builder in mind. KVP Gas Blocks feature a threaded gas tube retention pin that eliminates the installation awkwardness surrounding tiny gas tube roll pins! The KVP gas tube retention pin, gas adjustment screw, and the gas-block all install/adjust with the same 3/32" Allen wrench. NO additional tools required! FeaturesMachined from USA Steel and Black Oxide FinishedSet Screw (10-32) Spacing: .400"Allen Wrench: 3/32"Height: 1.41" Includes:(2) Set Screws(1) Gas Adjustment Screw(1) Threaded Gas Tube Pin Note: Thread locker is suggested.