【DRILL SIZE】 1 × (4-12 mm), 1 × (4-20 mm), 1 × (4-32 mm) step drill bit. The step drill bits have three sizes to meet your different needs. And the package contained a nylon bag. 【DOUBLE CUTTING BLADES】: Double cutting blades and X-type opening design ensure faster and smoother cutting; 3-sided shank design can prevent the drill chuck from slipping; With the slightest pressure, the sets can cut through wood, sheet metal, steel, and other surfaces. 【HEX SHANK】1/4" (6.35mm) hex shank works with most drills or drills with 1/4" chuck, fits securely into the chuck of power tools and eliminates slippage. 【HSS & TITANIUM COATED】Made of super strong HSS steel and coated with titanium, the titanium coating ensures easy cutting of steel, aluminum sheet, brass, copper, plastic, wood, etc. 【APPLICATION】Suitable for sheet metal, sink, auto repair, etc. Widely used for drilling holes in a variety of materials like plate, aluminum, insulation board, PVC board, wood thickness within 5mm.