13 Piece, Black Oxide Drill Bit Set, Helix Is 31&degree. Which Minimizes The Over Aggressiveness Of A True Parabolic Flute, 135&degree. Split Point For Quick Start & No Walk Applications, Parabolic Flute Design Improves Chip Ejection In Metal & Wood Drilling Applications, Black Oxide Coating For Greater Resistance To Wear, Industrial Grade Steel, For Drilling In Metal, Wood & Plastic, Set Contains Two 1/16″, 5/64″, Two 3/32″, 7/64″, Two 1/8″, 9/64″, 5/32″, 3/16″, 7/32″, 1/4″ Bits.