General description For use on a variety of surfaces including steel, cast iron, wood, brick, and more. This 18-piece combination drill bit set features a mixture of HSS, masonry, and wood drill bits, all supplied in a cylindrical plastic storage case. Technical specifications HSS Roll Forged Drill Bits (x6) - Sizes: 3mm, 4mm, 5mm, 6mm, 8mm, 10mm Milled Flute Sand Blasted Masonry Drill Bits (x6) - Sizes: 3mm, 4mm, 5mm, 6mm, 8mm, 10mm Brad Point Wood Drill Bits (x6) - Sizes: 3mm, 4mm, 5mm, 6mm, 8mm, 10mm