Ginsco 3pcs 4-12/20/32mm Large HSS Steel Step Drill Bit Set Hole Cutter Kits For Woodworking Size: 4-32mm(15 Step) Drop forged, heat treated, high speed steel, fully polish. Take the guessing out of drilling by supplying the proper depth for you. Use for home and industrial. Ideal for using to cut holes in a variety of materials Including steel, brass, wood, plastic, etc.