135° SPLIT POINT TIP: Each step down drill bit is made with high strength HSS and is black and cobalt-treated for added durability to ensure long service life and longevity. The design of the tip angle increases cutting speed with self-centering and prevents walking off the surface of workpiece. | 2 FLUTE DESIGN: This metric stepper drill bit has a two-flute design that clears chips faster, smoother, and allows particles to escape easily making cleaner holes at any worksite. | TRI-FLATTED SHANK: Each unibit optimally fits into power tools such as impact drill chucks securely and eliminates slip for higher efficiency of output. | HSS STEP BIT: This step up drill bit set cuts through steel, sheet metal, wood, plexiglass, enlarges a hole, and other surfaces creating relatively clean holes with only a small amount of pressure and deburrs as you drill. | MULTIPLE HOLE DRILL BIT: 6 millimeter shank: (9 steps- 4, 5 , 6, 7, 8 ,9 10, 11, 12 mm),(5 steps- 4, 6, 8, 10, 12 mm) and 8mm shank (7 steps- 6, 8, 10, 12, 14, 16, 18 mm),(10 steps- 4, 6, 8, 10, 12, 14, 16, 18, 20, 22mm) and 10mm shank (13 steps- 6, 8, 10, 13, 16, 18, 20, 22, 25, 28, 30, 32, 35 mm).