HSS step drill bits, sprial flute, 3 flat shanks M35, M42 Cobalt step drill, HSS step drill sprial fluteStep drill bits are perfect for drilling multiple-holes in thin sections of metal, plastic, wood with a single bit.Each step drill does many work of many drill bits sizes. Drill many round holes in most metals (steel , brass, Aluminium, Copper) up to 1/8" (3.2mm) thick as well as in plastic and ...