Magpul Enhanced Ejection Port Cover Black Polymer for AR-15, M4, M16 The Enhanced Ejection Port Cover is a drop-in upgrade designed to provide an improved installation process, physical strength, and corrosion resistance over the standard USGI ejection port cover. Traditional stamped-steel ejection ports are malleable, prone to corrosion, and require tools to install. The Enhanced Ejection Port Cover snaps into place easily without having to remove your hand guard or barrel nut, wind any loose springs, or adjust small e-clips. Constructed of impact-resistant injection molded polymer, it is corrosion resistant and will not bend or deform from impacts. Compatible with USGI-pattern AR15 upper receivers that accept USGI ejection port covers