Bits Step -Co Spiral Cobalt Hex Grooved Shank With Bag Tool Drill 3Pcs Tool&Home Improvment La Vida En Titanium Coated Step Drill HIGH SPEED STEEL: classic high speed steel with titanium coating for capability fits into power tools chuck securely and eliminates slip Increases cutting speed with self-centering and walking 1x 4-12mm Spiral Grooved Step Drill 4 - 12 mm 9 Steps (4mm 5mm 6mm 7mm 8mm 9mm 10mm 11mm 12mm) 7cm(L) Spiral Flute DESIGN | clears chips faster and allows particles to escape easily Package included: 4 - 20 mm 9 Steps (4mm 6mm 8mm 10mm 12mm 14mm 16mm 18mm 20mm) 7cm(L) 4 - 32 mm 15 Steps (4mm 6mm 8mm 10mm 12mm 14mm 16mm 18mm 20mm 22mm 24mm 26mm 28mm 30mm 32mm) 10cm(L) Surface : titanize 1x 4-32mm Spiral Grooved Step Drill 1x Portable bag Titanium Step Drill Bit High Speed Steel Quick Change 1/4 Shank Total 3-Piece Set Tool for Carbon Steel Sheet Iron Insulation Boards PVC Boards Planks and Wood 1x 4-20mm Spiral Grooved Step Drill