VIPER INTERNATIONAL-THE VIPER RIMFIRE/SPORTER BARREL TOP FEATURES: The Viper Rimfire/Sporter Barrel Top is just that. These tops are made to fit either the Viper (four-hole top) or the Python (two-hole top) barrel vise with rimfire/sporter barrels in mind. The tops will enable you to grip barrels as small as .500" to 1". To use the Viper or Python Barrel Vise Rimfire/Sporter top just remove the nuts and washers from your Viper or Python Barrel Vise. Keep the springs in place, put the Rimfire/Sporter top onto your vise. On a sporter barrel- grip the barrel several inches away from the receiver/action on an area of the barrel that will make ful Mfg: Viper Bench Rest