Centurion Arms Low Profile Non-Tabbed Gas Blocks .625, .750 and our Tabbed .750 for all current Centurion Arms barrels in 5.56, 300BLK and 6ARC with the gas block alignment notch!Our Low Profile .875 Tabbed and Non-Tabbed are available for our .308 and 6.5MM stainless barrelsAll current models a 2 set screw design with a spacing of .400 between the two scerws.Weight: .750 1.1oz .875 1.2oz .625 1.2ozAll options include required set screws and roll pinSet Screw Installation:Recommended Torque 25 in/lbs Use a quality Allen wrench (fully seated) and torque until you just start to see the wrench flex