Perfect for any rail system, these ultra-low profile gas blocks are the ideal companion for Faxon Firearms (or any other) barrels with a standard diameter gas journal. Made from high-strength steel, all our gas blocks are a matching black luster to our barrels. For lightweight builds, the block is drilled through the middle of the profile. The gas block clamps on to the barrel using 3 allen keys on the bottom of the block. *Faxon Firearms highly recommends the use of Loc-Tite or similar thread-locking compounds. Gas blocks will get very hot, so pick a compound according to your intended use of the firearm. Specifications (.625"):Barrel Compatibility: .625"Weight: .07 LbsWidth: 1.00"Height: ~1 & 7/32" Mounting: 3x Screws (Allen Key interface)