Description: 1180X type opening design is adopted to have easy self-centering positioning and effectively reduce slippery, this spiral flute step drill bit is easy and convenient to use. Double spiral flutes enable this sharp and anti-abrasion drill bit to punch accurately, remove chips quickly and smoothly and reduce cutting resistance, which is pretty practical. High speed steel and process of titanium plating make up of these spiral flute step drill bits. Its length is 10.1cm, its width and height are both 3.2cm. This set is suitable for iron plates, aluminum materials, insulating plates, PVC plates, wood boards and other materials with a thickness of 4MM. Item Name: Spiral Flute Step Drill Bits Material: High Speed Steel,Plating Titanium Specification: Spiral Flute Handle Type: Triangular Handle Cutting Diameter: 4-12mm(4mm, 6mm, 8mm, 10mm, 12mm), 4-20mm(4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm), 4-32mm(4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 24mm, 26mm, 28mm, 30mm, 32mm) Step Spacing: 5mm Features: Double Spiral Flutes, Sturdy, HSS Size Details: 6mm(4-12mm): Total Length: 65mm/2.56", Handle Length: 24mm/0.94", Head Length: 41mm/1.61", Steps: 5 Steps (Approx.) 8mm(4-20mm): Total Length: 73mm/2.87", Handle Length: 21mm/0.83", Head Length: 51mm/2.01", Steps: 9 Steps (Approx.) 10mm(4-32mm): Total Length: 101mm/3.98", Handle Length: 21mm/0.83", Head Length: 78mm/3.07", Steps: 13 Steps (Approx.) Notes: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Package Includes: 3 x Spiral Flute Step Drill Bits (4-12mm, 4-20mm, 4-32mm)