Alpha ThunderMax Step Drill Set Straight Flute 4-12,4-20,-6-30mm Metric Plastic Box STPSET3TM4 12mm 9 Steps 4, 5, 6, 7, 8, 9, 10, 11 & 12mm4 20mm 9 Steps 4, 6, 8, 10, 12, 14, 16, 18 & 20mm6 30mm 13 Steps 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28 & 30mmCut depth: Up to 3mmShank: Non slip 6mmSuits: Non hammer action portable power drillsCutting speed: 400 1,500 RPM2x LifeDrills & deburrs in one processSelf starting split point removes the need for a pilot holeTempered black finish maximises lubricant hold, therefore assisting chip flow &