This Compact Set Replaces 28 Individual Drill Bits Manufactured With Heat Treated HSS Coated With Titanium Nitride Two Flute Design For Faster, Smoother Cutting For Drilling Holes in Thin Material Such as Steel, Stainless Steel, Copper, Alum Self-Starting, No Walking & Center Punch is Not Required 3/16" to 1/2" Six Step Bit 1/4" Shank 1/4" to 3/4" Nine Step Bit 1/4" Shank 1/8" to 1/2" Thirteen Step Bit 3/8" Shank