The AR-15 Stripped Upper Receiver is one of Aero Precision's most popular products. Forged from 7075-T6 aluminum, this stripped upper is precision machined to mil-spec M16/M4 specifications. Match this upper with one of Aero Precision's AR-15 lower receivers for a solid and dependable fit. Port door opening has been enlarged to fit .458 SOCOM and other similar rounds (.450 Bushmaster, .50 Beowulf, etc.) Works with AR-15 lower receivers .250 takedown pin holes Laser engraved T-marks "XL" portion of Aero Logo on Tang Compatible with AR15 port door and forward assist Weight: 8.35 ounces Mfg: Aero Precision