These Wilson Combat AR-15 Ejection Port Covers give you the ability to quickly identify upper receivers of various calibers.  Finished in Black Armor-Tuff®, the covers feature the caliber of your choice.  Replaces your existing ejection port cover.  Available calibers include: 5.56mm NATO, 6.8 SPC II and 300 BLK.  Includes the ejection port cover only, no pin, c-clip or spring.