DoubleStar Picatinny Rail Lightweight Gas Block Black .625in. Incorporates the 1913 picatinny rail. This gas block is secured using 4 set screwsinserted at 45degree angle. Specifications for DoubleStar Picatinny Rail Lightweight Gas Block: Manufacturer: DoubleStar Color: Black Fabric/Material: 7075-T6 Aluminum Size: One Size Gun Make: AR Platform Gun Model: AR-15 Condition: New Features of Doublestar Picatinny Rail Lightweight Gas Block Size: .625" Finish: Hard coat anodized Package Contents: DoubleStar Picatinny Rail Lightweight Gas Block What firearm models does the manufacturer say DoubleStar Picatinny Rail Lightweight Gas Block is compatible with? The manufacturer suggests that DoubleStar Picatinny Rail Lightweight Gas Block is compatible with AR-15DoubleStar AR452: Picatinny Rail Lightweight Gas Block Black .625in