Capri Tools 10244 ST-244 Step Drill Bit Set, 28 Step Size Step drill bits give you the ability to gradually drill larger holes than standard bits Strong and capable of drilling holes in steel, copper, plastic, aluminum, and other similar materials Contains 3 pieces (3/8, 1/4, 1/4-in shanks) with 28 step sizes (1/4-3/4, 3/16-1/2, 1/8-1/2-in) Each bit has titanium coating for long-term durability Their tri-flat design gives them maximum grip in your drill