This quality Irwin 4 Unibit Self Starting Stairste 3/16-7/8 in. step drillStep drill that produces true, round holesNon skid tip means no need for center punches3 flattened shanks prevent drill chuck slippingNew SpeedPoint tip penetrates faster than previous Unibits and prevents walkingIdeal for drilling holes into thin materials such as stainless steel, copper, brass, aluminum, plastic and laminates3/16 in., 1/4 in., 5/16 in., 3/8 in., 7/16 in., 1/2 in., 9/16 in., 5/8 in., 11/16 in., 3/4 in., 13/16 in. and 7/8 in. #4