This handy little punch is made for just one purpose . . . to drive the front sight in or out without marring it or the barrel. We first tried Brass, but as you know, it leaves a "Brass tracking" wherever it rubs. We then tried fiber, but after a few hard blows it shatters. NYLON doesn't mark the barrel or sight, nor does it shatter or lose its shape after hard and prolonged use. Mfg: Brownells SPECS: 4" (10.2cm) long. 5/16" (7.9mm) diameter. Polyenco Nylon. Sold in a set of 3.