Features: Made of superior high speed steel, firm and long-lasting. Nitride coated, has nice heat resistance, corrosion resistance and rust resistance. No need for a pilot hole, can automatically deburr holes as you drill. Special step stucture, can drill different size of holes. Working with water cooling, can effectively extend the service life of bit, drilling speed 250-400 recommended. Apply to thin iron plate, steel board, wood, aluminum, insulation panels, PVC sheet, ect. Specifications: Material: high speed steel Coated: nitride coated Color: black Quantity: 4pcs Includes: 3pcs bit (4-12mm/4-20mm/4-32mm) & 1pc center Punch Bits detail: 4-12mm: 4-6-8-10-12mm (5 steps) 4-20mm: 4-6-8-10-12-14-16-18-20mm (9 steps) 4-32mm: 4-6-8-10-12-14-16-18-20-22-24-26-28-30-32mm (15 steps) Package size: 150 * 100 * 40mm / 5.9 * 3.94 * 1.57in Package weight: 281g / 9.91ounces Note: Due to the different display screen and light effect, the actual color of the item might be slightly different from the color showed on the pictures. Package List: 3 * Drilling Bits 1 * Center Punch