Easily removes the sharp outside edge that remains after shortening or crowning a barrel. Easy-to-use cutter requires only a hand drill to quickly cut a smooth radius for a nicely finished look. Three cutter sizes to fit most barrels. Mfg: Brownells SPECS: Hardened Steel. .615" (15.6mm), .715" (18.1mm), .815" (20.7mm), .920" (23.4mm) cutter diameters.