Specifically designed at the request of the U.S. Marine Corps, the EMOD A5 stock system enhances both operator comfort and the reliability of the rifle. With seven length-of-pull adjustment positions at .65" increments, the A5 system can offer a longer length of pull than an M16A2 fixed stock, yet collapses to the same length as an M4 carbine. A5 Receiver Extension and A5 Spring/Buffer kit are sold separately to enable upgrading an existing carbine to the longer, 7-position extension for use with other mil-spec M4-type buttstocks. Mfg: Vltor Weapon Systems SPECS: A5 Receiver Extension accepts M4-type buttstocks that fit mil-spec 1.15" O.D. receiver extension.