Hougen 17128 RotaLoc 3/4 D.O.C. 7/8-Inch Diameter is designed for use with the Hougen HMD115 Ultra-Low Profile Truck Frame Drill. The RotaLoc cutters are made of M42 high speed steel and feature Stack Cut geometry for penetrating multiple plates in a single pass, up to 3/4-inch depth of cut. The RotaLoc cutters feature a 5/8-inch bayonet-style shank mounting for fast change out, with no other tools required to install in the drill spindle, and can be as easily removed. For optimum cutter tool life and cutter efficiency, use Hougen Slick-Stik Lubricant. The 17128 RotaLoc annular cutter is to be used with Pilot 17100 or 17101, and has a decimal equivalent of .8750.