DT4957-QZ 9 piece HSCo Drill Set 1mm to 13mm. the high-performance Extreme 2 Drill Bit set by DeWALT. This easy to use set with the innovative tapered web on each bit provides greater durability and reduces breakage, while the metal tip only starts drilling on contact. This is to ensure clean and accurate holes and at the same time cutting down on lock-up on breakthrough. These HSS-Co Extreme drill bits can make light work of various sheet metals, as well as wood and plastics, but they are especially good at tackling stainless steel and are an essential addition for anyone using a drill.