Ideal for metal sheets, plastics, wood. 3 drill sizes: 4 - 12 mm, 4 - 20 mm and 4 - 32 mm , heat-treated, high-speed steel, complete polishing Take the guessing of drilling by providing the right depth . Dimension: 1:4 mm to 12 mm 9 steps (4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm), 7cm (L) 2:4 mm to 20 mm 9 steps (4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm), 7cm (L) 3:4 mm to 32 mm 15 steps (4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 24mm, 26mm, 28mm, 30mm, 32mm), 10cm Note: When drilling the hardness and hole of larger diameter, the bit must cool, with cold water cool the drilling for 120 to 240 is extended for the processing of 6 mm and the plate, the bits of high-speed steel material, drilling 120/ , drilling more than 20 mm, drilling not more than 400 RPM and water cooling. Package: 3pcs hex HSS spiral groove stage drill with transparent plastic boxes set Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.