TacFire Low Profile Micro Gas Block .750in Black Oxide Steel. It is Heat treated Erosion resistant with a Black Oxide Finish. It is compatible with a .750 diameter barrel. Roll pin and set screws are included. Specifications for TacFire Low Profile Micro Gas Block: Manufacturer: TacFire Color: Black Fabric/Material: Steel Gas Block Journal Size-Diameter: .750 in Gun Make: Universal Gun Model: Universal Weight: 1.5 oz Finish: Black Oxide Package Contents: TacFire Low Profile Micro Gas Block What firearm models does the manufacturer say TacFire Low Profile Micro Gas Block is compatible with? The manufacturer suggests that TacFire Low Profile Micro Gas Block is compatible with UniversalTacFire MAR001S2: Low Profile Micro Gas Block .750in Black Oxide Steel