This Irwin 10502500 HSS Pro is an industrial quality 19-piece twist drill bit set with outstanding performance and long service life. They are designed for drilling steel and steel castings, alloyed and non-alloyed steel, cast iron, non-ferrous metals, plastics, and other materials. The 118 split point shape provides an optimum centering when starting, and a faster drilling rate. There is no need to pre-punch or use a pilot drill they penetrate quickly, and require little effort / feed pressure. The bits are highly accurate, and are made from high-performance high-speed steel. Set of 19 HSS Pro Drill Bits 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9. 9.5 and 10mm. Supplied in a metal case.