The Aero Precision EPC Buffer Kit features the Aero Precsion Enhanced Carbine Buffer Tube and their 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. Can be purchased as an assembly, or as the buffer alone. EPC Buffer 308 Carbine Buffer Spring Enhanced Carbine Buffer Tube Mil-Spec Receiver End Plate Mil-Spec Castle Nut Stock NOT Included Note: For use in a 40S&W, 10mm, or 45ACP build we recommend the use of a heavier buffer spring. Mfg: Aero Precision