MOD 2 4140 Steel Body Buffers have a unique fluted design with minimum contact points, allowing debris to clear easily, while the FNC LIFE HD treatment chemically bonds in lubrication for smoother cycling. H2 .308 Weight- 4.4 oz. Used for .308 applications and ships with all MK2 series complete lowers and rifles. Shortened to work with AR-10 platforms using standard buffer tubes