The ST-T3 buffer provides a firmer recoil impulse and is intended for machine guns, suppressed weapons and rifles that suffer from overgassing. It doesn't have any fluids to leak out like some other buffers, so it's maintenance free. Laser engraved with the Spike's Tactical Logo. Each ST-T3 buffer contains three sliding solid weights cut from tungsten bar stock and topped off with a Mil-Spec bumper. The ST-T3 eliminates the chance of bolt bounce, helps with muzzle rise when firing in full-auto, and cuts down on felt recoil. It's designed for .223/5.56 but it works in all calibers.