This Vltor Standard H2 A5 Recoil System Buffer is a high quality replacement component for an AR-15 rifle that's equipped with the Vltor A5 Recoil System. The H2 Buffer is the standard weight unit supplied with all A5 Recoil System Retrofit Kits as well as the A5 EMOD Stock Assembly. H2 buffer weight is 5.3 oz.