Our barrel vise jaw is a 2 piece set and works great for both rifle and pistol barrels. These are made from non-anodized 6063 F hard extruded aluminum so that you will get a better grip on the barrel and not mar the finish. These are designed for just about any diameter barrel. They drop into your vise for clamping, are very easy to use, and grip the barrel so you can install muzzle brakes, clean the bore and chamber, or perform other maintenance. This is a must-have for the firearm enthusiast or anybody with a straight or lightly tapered barrel (the chamber area on most rifles is not tapered). They will also work on slightly tapered barrels, such as the 10/22. Features and Benefits Made from 6063 as extruded aluminum. Made for just about any diameter barrel. These are not V blocks, they are U blocks. They are made for a 3/4 inch / 19mm diameter barrel. A smaller barrel will be gripped on the flats of the larger radius. A larger barrel will be gripped by the edges of the radii. Just clamp down with your vise and the barrel won't spin. Forget those welded, screw together clamps; use these instead. You can clamp the action on the flats and the barrel in the groove. No wood blocks or split bushings, spacer, or sleeves here. Get the full clamping power from a vise, not two screws. Lifetime guarantee. Designed, developed, and manufactured in the USA.