When you are thinking about building a new AR-15 rifle or completing that lower you have had sitting around this CMMG AR-15 Carbine Receiver Extension Kit 6-position Mil-Spec is the perfect one. This kit contains an AR-15 carbine receiver extension" end plate" carbine buffer and spring.

Features:
Designed to work with both standard 5.556mm NATO AR rifle builds
High quality anodized aluminum