Halls BSM6 Bradrad® Tool 8-38mm with 10mm Shank Halls MC 1M High-Speed Steel Step Drill 4-12mm Halls MC 2M High-Speed Steel Step Drill 10-20mm Halls MC 3M High-Speed Steel Step Drill 20-30mm Halls MC 4M High-Speed Steel Step Drill 4-12mm Halls MC 5M High-Speed Steel Step Drill 6-24mm Halls MC 7M High-Speed Steel Step Drill 4-20mm Halls MC 10M High-Speed Steel Step Drill 4-30mm Halls TMC3040 High-Speed Steel Step Drill 30--40mm Draper Step Drill Bit, 4 - 20mm Halls BSM2 Bradrad® Tool 6-36mm with 10mm Shank