All of SADLAK's Gas Blocks are made in the USA by craftsmen with years of experience delivering consistent quality. All the bores are precision honed and all critical measurements are 100% inspected to insure consistency and quality. Available in a multitude of sizes and styles, Sadlak's Gas Blocks are a great option if you are building an AR or if you are just looking to upgrade. The Gas Blocks are available in .625", .750", .875", or .936". They also feature option such as Clamp-Style, Slip-On, Skeletonized, or Adjustable, and all attaching hardware is included. All Gas Blocks except for the Picatinny Rail Gas Block are Low-Profile. Finishes inclu Mfg: Sadlak Industries SPECS: 6061 T6 aluminum, hardcoat anodized, black, or 1018 alloy steel, Parkerized, black. Barrel O.D. measured at gas port. SKU BBL. DIA. LENGTH WIDTH HEIGHT WEIGHT 100-006-899 .625"