Luth-AR Gas Block .750 Diameter Black. Each gas block will fit securely into a healthy AR platform to ensure that the gas port sizing does not contribute to excess wear and tear of the part. Luth-AR gas block fits securely into an AR platform to ensure that the gas port does not get pinched when installing/removing the bolt. To be used on a AR platform with a Luth-AR bolt carrier group or piston system the gas block should be installed at the bolt carrier early stage in the gas system build. Then the locking lug can be installed at this point to fully secure the gas block to the barrel. Specifications for Luth-AR Gas Block: Manufacturer: Luth-AR Color: Black Fabric/Material: 4140 Chrome Moly Steel Caliber: .223 Remington Gun Make: AR Platform Gun Model: AR-15 Features of Luth-AR Gas Block Two 8-32 Set Screws (requires a 3/32 Allen wrench) 1 Roll Pin Double Inspected and highest quality Package Contents: Luth-AR Gas Block What firearm models does the manufacturer say Luth-AR Gas Block is compatible with? The manufacturer says that Luth-AR Gas Block is compatible with AR-15Luth-AR GB-LP750: Gas Block .750 Diameter Black