This professional 3-piece step drill set features an optimized spiral flute design for superior performance. The cobalt-alloyed HSS construction withstands high-temperature drilling. Covers hole sizes from 6mm to 32mm in precise increments. The 135° split point starts holes accurately without center punching. The bright finish reduces friction and heat buildup. The 3/8" reduced shank fits most drill chucks securely. Ideal for stainless steel, aluminum, and other tough materials. The precision-ground cutting edges produce burr-free holes. The balanced design minimizes vibration for better control. Includes protective storage case. A top-tier solution for metal fabricators and HVAC professionals.