KAK AR-15 Upper Receiver Completion Kit Forward Assist/Ejection Port Cover. 56x45mm NATO Gun Model: AR-15 Condition: New Package Contents: KAK AR-15 Upper Receiver Completion Kit What firearm models does the manufacturer say KAK AR-15 Upper Receiver Completion Kit is compatible with? The manufacturer suggests that KAK AR-15 Upper Receiver Completion Kit is compatible with AR-15KAK AR-KT-18: AR-15 Upper Receiver Completion Kit Forward Assist/Ejection Port Cover