Converts an AR-15 to shoot 5.7x28 FN. Unique upper design loads on top and accepts FN PS90 magazine (not included) and ejects downward through the AR-15 magwell. Upper is precision machined from a one piece aluminum forging. Integrated picatinny-style quad rail system allows attachment of various accessories. Parkerized chrome alloy bolt and full-floated barrel. Teflon-infused hard coat anodized aluminum upper and rails.