Adjustable Weight extended length Ar15 9mm buffer. The buffer is 4″ long and is adjustable from 4.9oz to 10oz. This kit includes the buffer body, 4 aluminum weights , 4 steel weights, 4 tungsten weights, 5 rubber spacers, 2 pins and 2 rubber tips. Use with your current or our custom recoil springs to fine tune your 9mm Ar15 rifle. This 4″ long buffer will short stroke your recoil system approximately .75″ in a standard carbine length buffer tube.