Guntec USA AR-15 Ejection Port Dust Cover Assembly Gen 3 Anodized Black. 223 Remington Features of Guntec USA Gen 3 AR-15 Ejection Port Dust Cover Assembly Complete Assembly - Includes Dust Cover Rod Spring And Clip Adjustable Set Screw Allows Proper Alignment For Opening And Closing On Receiver Gen 3 Design Recommended For Billet Uppers Only Package Contents: Guntec USA Gen 3 AR-15 Ejection Port Dust Cover Assembly What firearm models does the manufacturer say Guntec USA Gen 3 AR-15 Ejection Port Dust Cover Assembly is compatible with? The manufacturer suggests that Guntec USA Gen 3 AR-15 Ejection Port Dust Cover Assembly is compatible with AR-15Guntec USA 223GATE-G3-BLACK: AR-15 Ejection Port Dust Cover Assembly Gen 3 Anodized Black