M4/A3-style upper receiver is available stripped. Precision machined from a 7075 T6 aluminum alloy forging to USGI dimensions, and ready to mate with the mil-spec lower and internal components of your choice. Includes M4-type feed cuts and alphanumeric position markers stamped into the rail slots. Hardcoat anodized to resist wear, add strength, and protect from corrosion. Hard dry-lube surface treatment protects the anodizing from scuffs and reduces friction between bolt carrier and receiver walls for ultra-smooth operation, less wear, and longer service life. Mfg: D.S. Arms SPECS: 7075 T6 aluminum, hardcoat anodized, dry-lube finish, matte black. .250″ takedown/pivot pin holes.