AT3 Tactical AR-15 Ejection Port/Dust Cover Assembly. If youre looking to replace an existing dust cover check out this guide Specifications for AT3 Tactical AR-15 Ejection Port Cover Dust Assembly: Manufacturer: AT3 Tactical Gun Model: M16 AR-15 Features of AT3 Tactical AR-15 Ejection Port Cover Dust Assembly Mil-Spec Ejection Port Assembly Made for AR-15/M16 Package Contents: AT3 Tactical AR-15 Ejection Port Cover Dust Assembly Ejection Port Cover Door Ejection Port Cover Rod with c-clip Ejection Port Cover Spring What firearm models does the manufacturer say AT3 Tactical AR-15 Ejection Port Cover Dust Assembly is compatible with? The manufacturer suggests that AT3 Tactical AR-15 Ejection Port Cover Dust Assembly is compatible with AR-15 M16AT3 Tactical AT3-EPA-02: AR-15 Ejection Port/Dust Cover Assembly