The AR15 Stripped Upper Receiver is one of our most popular products. This stripped upper is precision machined to mil-spec M16/M4 specifications and features M4 feedramps. Match this upper with one of our AR15 lower receivers for a solid and dependable fit. Features- Port door opening have been enlarged to fit .458 SOCOM and other similar rounds (.450 Bushmaster, .50 Beowulf, etc.), M4 Feedramps, .250 takedown pin holes, laser engraved T-marks, and "XL" portion of Aero Logo on Tang. Works with AR15 lower receivers, compatible with AR15 port door and forward assist. Works with standard AR15/M16 components. Made in the USA.