Features: High speed steel material, more durable.Nitride coated to reduce friction and run No need for a pilot hole, can automatically deburr holes as you drill. step stucture, can drill different size holes, 1 step drill can be used as 1 box of drill bit. Working with water cooling, can effectively extend the service life of bit,drilling speed 250--400 recommended.Widely used to cut holes of material like thin steel board, wood, thin iron, aluminum alloy,insulation boards, PVC sheet,. Type: Spiral Step Drill Bit Coated:Nitride Coated Handle:Triangle Scop: Thin iron plate,aluminum,insulation panels,PVC panels 0.4mm thickness within the timber. 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 Colour:black Material:high speed steel Package Contents: 1 x 4-12mm drill head 1 x 4-20m drill head 1 x 4-32mmm drill head Only the above package content, other products are not included. Note: Light reflection 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.