Dewalt qz extreme 2 metal drill bits 49 151mm pack of 10 dewalt dt5559 qz these 110 x 142mm drill bits from dewalt have been manufactured to a very high standard courtesy of the innovative tapered web which greatly reduces breakage while the gold ferrous oxide coating prevents overheating for longer bit life whether you are a profressional tradesman or diy enthusiast the drill bits are ideal for portable drilling of steel alloyed and non alloyed up to 900nmmsup2 and for drilling