CMC Triggers AR-15 Ejection Port Cover Assembly Black Small. This is a complete mil-spec AR-15 trapdoor kit so you get the door assembly the spring the rod and the C-clip all together. The rod is machined from stainless steel and finished in black nitride which is a step up from the plain steel rods that tend to rust. It installs on any standard AR-15 upper. Specifications for CMC Triggers AR-15 Ejection Port Cover Assembly: Manufacturer: CMC Triggers Color: Black Gun Model: AR-15 Gun Make: AR Platform Package Contents: CMC Triggers AR-15 Ejection Port Cover Assembly What firearm models does the manufacturer say CMC Triggers AR-15 Ejection Port Cover Assembly is compatible with? The manufacturer says that CMC Triggers AR-15 Ejection Port Cover Assembly is compatible with AR-15CMC Triggers CMC-DC-STD: AR-15 Ejection Port Cover Assembly Black Small