KVP's 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 and the gas-block install with the same 3/32" Allen wrench. NO special tools required! Note: Thread locker is suggested. FeaturesMachined from USA Steel and Black Oxide Finished.Set Screw (10-32) Spacing: .400"Allen Wrench: 3/32"Height: 1.41" Includes(2) Set Screws(1) Threaded Gas Tube Pin