Machined aluminum hydraulic buffer drops into any standard carbine buffer tube to absorb recoil, slow cyclic rate of fire on full-auto ARs, and suppress bolt bounce. Linear deceleration technology helps increase service life of parts by reducing the force of impact, and softer recoil impulse is easier on optics. Less recoil aids in fast follow-up shots, too. Durable high-impact steel striker cap withstands long use. Works with any standard carbine buffer spring. Mfg: Crosshair SPECS: Machined aluminum exterior, green anodized finish, steel striker cap. 3 1/2" (8.8cm) long, .95" (2.4cm) O.D. 3.2 oz. (91g) wt. For use on rifles fitted with M4-type collapsible buttstock.