Features Faster And Smoother Cutting: The four spiral grooves and precision cutting blades provide exceptional cutting efficiency, making tasks effortless and enjoyable Versatile High-Speed Performance: Engineered for high-speed drilling, this bit excels in cutting through stainless steel, metal sheets, wood, plastic, aluminum, and copper Exceptional Hardness For Tough Materials: With a hardness rating of 89HRC, this drill bit easily tackles harder materials while maintaining impressive cutting speeds Durable M35 Cobalt Steel Construction: Crafted from M35 cobalt steel, this bit offers superior heat resistance, strength, and long-lasting durability for all your drilling needs Wide Range Of Sizes: Featuring 9 sizes ranging from 4mm to 12mm, it includes a 1/4 inch shank for seamless compatibility with various drilling machines Features: 1、Faster And Smoother Cutting: The four spiral grooves and cutting blades of this step drill bit ensure quicker and smoother cutting, making it feel like cutting through butter. 2、High Speed: Made from high speed design, this step drill bit is for drilling stainl steel, metal sheets, wood, plastic, aluminum, copper, and other metal plates. 3、High Hardn: With a hardn of 89HRC, this step drill bit can cut through harder materials and achieve higher cutting speeds. 4、Material: The step drill bit is made from M35 cobalt steel, which is known for its excellent heat resistance, strength, and durability. 5、Diameters: Designed to drill holes in nine different sizes ranging from 4mm to 12mm, and it features a 1/4？inch shank for easy compatibility with various drilling machines. Specification: Item Type: Step Drill Bits Material: M35 Cobalt Hole Diameter: 4-5-6-7-8-9-10-11-12mm/0.2-0.3-0.4-0.5in Shank Diameter: 1/4 inch Package List: 1 x Step Drill Bit 1 x Storage Box Package List 1 x Step Drill Bit 1 x Storage Box