TTP HARD drills Set 1Mm To 10Mm X 0.5Mm (19 Drill Bits), Metric Cobalt Drill Set For Drilling Harder Metals Stainless Chrome Aluminum Cast Iron makes drilling all metals easier prolongs the life if the drill bit assists in reducing heat build up adheres to drill bit unlike sprays Mechanics Fitters Home improvement enthusiasts Locksmiths Imperial sizes Metric Sizes Individual drill bits Packs of 10 Sets Metal cutting paste Drill slowly (gradually increasing speed if you feel appropriate) Use light pressure (allow the drill bit to do the work) Use lots of lubricant Take breaks (approx every 10 seconds to prevent drill bit overheating) Cobalt drill bits are ideal for drilling harder metals. Drill slowly Take breaks to avid heat build up Use a good quality lubricant, this will: Assist in lubricating the drill bit and the cutting surface Prolong the life of your drill bit Assist in prevention of excessive heat build up Always wear eye protection Ensure the item you are drilling is secured properly Ensure your drill is maintained and in safe working order