DoubleStar Picatinny Rail Bull Gas Block Black .937in. Machined from 6061 T6 aluminum and hard coat anodized. Incorporates the 11913 picatinny rail. This gas block is secured using 4 set screws inserted at 45. .937 Bull Specifications for DoubleStar Picatinny Rail Bull Gas Block: Manufacturer: DoubleStar Color: Black Fabric/Material: 7075-T6 Aluminum Gas Block Journal Size-Diameter: .937 in Size: One Size Gun Make: AR Platform Gun Model: AR-15 Features of Doublestar Picatinny Rail Bull Gas Block Size: .937" Bull Finish: Hard coat anodized 4 angle set screws ensure block stays tight during heavy use Package Contents: Doublestar Picatinny Rail Bull Gas Block What firearm models does the manufacturer say DoubleStar Picatinny Rail Bull Gas Block is compatible with? The manufacturer suggests that DoubleStar Picatinny Rail Bull Gas Block is compatible with AR-15DoubleStar AR454: Picatinny Rail Bull Gas Block Black .937in