Dewalt qz extreme 2 metal drill bits 34 151mm dewalt dt5057 qz this 105 x 133mm drill bit from dewalt has 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 professional tradesman or diy enthusiast the drill bit is ideal for portable drilling of steel alloyed and non alloyed up to 900nmmsup2 and for drilling a sheet or thin mat