Greenlee Kwik Stepper Step Bit Kit, Dual Flute Cutting Edge, 1-3/8 in Cutting Diameter, 2 Step, 1/ST | AFT Fasteners
Greenlee GSB12 1-3/8" Step Bit (#12) Metal Cutter with Patented Split-Step Design, 1-3/8" Metal Cutting Tool for 1/2" Drill Chucks: Amazon.com: Industrial & Scientific
Edmondson Supply | Greenlee GSB06 1/2" Step Bit (#6)
Greenlee 30008 1-1/8" Electricians Multi-Hole Stepper Step Bit 30008 GRE30008 - Gas and Supply
Greenlee Step Bit 3/8-in 4-Step Drill Bit (3/16-in to 7/8-in) in the Step Drill Bits department at Lowes.com