Amazon.com: M35 Four Spiral Flute Step Drill Bit Set 1/4" - 1-3/8" (19 Sizes), 1/4" Hex Shank Drill, Impact Resistant M35 Cobalt Step Drill Bit, for Stainless Steel, Wood, Aluminum, Plastic :
JNB PRO Countersink Drill BIT Set for Metal - 5 PC HIGH Speed Steel with 5% Cobalt HSS-Co M35 Grade, Sizes 1/4", 3/8", 1/2", 5/8" & 3/4" - 5 Flutes 82 Degree -
JNB PRO Countersink Drill BIT Set for Metal - 5 PC HIGH Speed Steel with 5%
Milwaukee 8-32 NC Straight Flute Plug Tap & #29 Drill Bit 49-57-5521 - The Home Depot