Denmark IRWIN's JORAN revolver Carbide-tipped straight shank drills: 
 Drill diameter 3MM ---- 28MM. 
 Material: hard head & solder alloy inserts. Luxembourg CERATIZIT using special carbide tip, easy to drill the hardest of HRC58 degrees of super-hard material. Patented a special solder, to prevent drilling high temperature melt. The new single-flute design, chip removal efficiency 28%, thus effectively reducing the temperature of the mouth drilling to extend the service life. Special surface treatment process to prevent corrosion. 
 Application: Ideal for drilling heat-treated tool steel, cast iron hardness up to HRC58 or so super-hard material. 
 Caution: When drilling hard materials, please use the coolant and drilling materials according to different, appropriate adjustment speed and feed rate drilling.