IRWIN Tools 10502ZR Unibit Sheet Metal Step Drill Bit Set is a selection of the most popular Unibit step drill bits in the low diameter range (below 7/8 in.). Ideal for drilling true round holes with precise control in a variety of materials like sheet metal. metal plates. aluminum. fiberglass. plastics. plexiglass. and wood. The specially designed cutting edge drills true. round holes for a smooth. clean finish. and the SpeedPoint tip penetrates fast. prevents in.walking. in. and eliminates the need for a pilot/starting hole. The hex shank provdes a secure grip in the drill chuck. Plus. the permanent laser-etched sizes inside the flute are easy to read for precise control during the hole enlarging process. Contains: Unibit #1 with 13 hole sizes (1/8 in. to 1/2 in. by 32nds). Unibit #2 with 6 hole sizes (3/16 in. to 1/2 in. by 16ths for deeper steps). and Unibit #3 with 9 hole sizes (1/4 in. to 3/4 in. by 16ths). Product made in USA.