Morse, SDSS06 (124454), Switchback, high speed steel step drills is for precision hole cutting in materials from plastics to metal. Self starting drill point, combined with spiral flute, allows for faster penetration and cutting. With 1/16" incremental steps, hole diameters can gradually increase from 1/4" to 3/4" (total of 9 steps). Shank designed to work with 1/4", quick change, impact arbor adaptors. One (1) step drill per box.