San Tan Tactical Low Profile AR-15 Gas Block is a low and narrow, one-piece block designed to fit inside most free-float hand guards. Securely attaches to the barrel with included dual hex head set-screws. Fitted for AR15's with a barrel .750" O.D. at gas port and works in conjunction with all San Tan Tactical AR-15 Nitride Gas Tubes or standard Mil-Spec gas tubes and hardware. FeaturesLow Profile Machined from 17-4PH Stainless Steel Weight: 1.4 oz Dimensions: 1.35(ht) 1(ln)