The Aero Precision EPC Buffer Kit features Enhanced Carbine Buffer Tube and 7.7oz buffer and spring specifically optimized for use in the Aero Precision EPC. The 7.7oz EPC buffer, it is not intended for use in AR15 or M5 platforms. The additional length and weight will not allow for proper cycling of standard platforms.imageEPC 7.7 oz Buffer Kit includes:EPC Buffer308 Carbine Buffer SpringEnhanced Carbine Buffer TubeMil-Spec Receiver End PlateMil-Spec Castle Nut