3Pcs HSS 4-12/20/32mm Steel Step Drill Bit Large Cone Titanium Set Ideal for using to cut holes in a variety of materials including steel, brass, wood, plastic, etc. Step drill cutting specification : 4-12mm Hole Sizes in 2mm Steps (5 steps). 4-20mm Hole :9 steps. 4-32mm Hole:15 steps. Length : 4-12mm length : Appox. 6.3cm/ 2.48inch 4-20mm length : Appox. 7.3cm/ 2.87inch 4-32mm length : Appox. 10cm/ 3.94inch Heat treated and highly polished. Drills perfectly round holes in steel, brass, plastic, wood etc.