#4 (1/8" Drill Diameter) 60 Degree M42 8% Cobalt Combined Drill & Countersink Made of M42 steel for longer tool life. <br> Ground from solid. <br> Plain style. <br> Used for centering work ends where the work piece is to be revolved on machine centers. <br> 60 Degree countersink angle fits all standard centers. <br> 5/16" body diameter. These are a bright finish cobalt and are not marked M42.