Brand Features: Unique ladder structure allows for multiple aperture sizes. Capable of deburring, chamfering, and hole opening, functions not possible with standard twist drills. Requires no center punch; can carve clean apertures without pre-punching. Use water for cooling during operation to effectively extend tool life. Suitable for deburring, chamfering, elliptical hole enlargement, and use with twist drills, drills, and table drills. Widely used for cutting holes in various materials such as steel, wood, thin iron, aluminum alloy, insulation boards, and PVC sheets. Recommended drilling speed: 250400 rpm. Best suited for materials with hardness under 25 and plate thickness under 5mm. Step drill bit only; other accessories shown in images are not included. Specifications: Material: HSS Size: Approximately 10x98mm / 0.39x3.86in Style: 4-42mm (4, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42mm) Color: Golden Quantity: 1 Piece Note: No retail packaging. Please allow 01cm error due to manual measurement; ensure you are comfortable with this before purchasing. Due to differences in monitor displays, the actual color may vary slightly from the image. Package Includes: 1 x Step Drill Bit