Product Description IRWIN Tools 10225 Unibit Sheet Metal Step Drill Bit Set is a selection of the most popular Unibits that cover a wide range of applications. Ideal for drilling true, round holes with a smooth, clean finish in a variety of materials like sheet metal, metal plates, aluminum, fiberglass, plastics, plexiglass, and wood. The SpeedPoint tip penetrates fast, prevents "walking," and eliminates the need for a pilot/starting hole. The hex shank provdes a secure grip in the drill chuck. 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" to 1/2" by 32nds), Unibit #2 with 6 hole sizes (3/16" to 1/2" by 16ths for deeper steps), Unibit #4 with 12 hole sizes (3/16" to 7/8" by 16ths), and Unibit #21 with 10 hole sizes (13/16" to 1-3/8" for hole enlarging). Product made in USA. From the Manufacturer Irwin's Unibit SpeedPoint combines the most desired features of a Step Drill, speed and control and as many as 13 different sizes onto one single-fluted step drill bit. Irwin Industrial Tools 10225 2254-Piece General Purpose Set (10231, 10232, 10234, 10221)