Specifical step design, one drill for many sizes, very convenient. . Cutting material: iron sheet, aluminum, insulation board, PVC plate wood thickness in 4mm.The hole with a drill can play a variety of. Type:step drill Material:High speed steel colour:black Package Contents: 1 * 4-12mm drill 1 * 4-20mm drill 1 * 4-32mm drill 1 * Storage Bag Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.