1/4" to 1-3/8" HSS Spiral Flute Step Drill Bit Set Triangle Shank Countersink Titanium Coated Drill Bits Tool Set Wide application:The sharpness and titanium coating ensures easily cut through most sheet metal,aluminum sheets, wood board, plastic board, and some other materials with ease Made of super strong high speed steel together will titanium coating, which lasts the bit a long service life. Let you feel drill holes on metal like a hot knife through butter Easy drilling:Two-fluted design provides faster, smoother cutting; Provided with small pressure and the sets can cut through wood, sheet metal, steel and other surfaces Titanium high speed steel with high capability and durability in drilling holes in plastic, aluminum, copper, stainless steel and many other types of sheet metal Steps: 1/4", 3/8", 1/2", 5/8", 3/4", 7/8", 1", 1-1/8", 1-1/4", 1-3/8"