Features: Unique ladder structure allows for multiple aperture sizes Can deburr, chamfer, and enlarge holes, functions not possible with standard twist drills Precision cutting design enables clean hole creation without the need for a center punch Use water during operation to cool the bit and extend service life Ideal for deburring, chamfering, and elliptical hole enlargement Suitable for use on various materials including steel, wood, thin iron, aluminum alloy, insulation boards, and PVC sheets Recommended drilling speed: 250–400 rpm Designed for materials with hardness under 25 HRC and plate thickness under 5mm Includes 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 Allow 0–1cm measurement deviation due to manual measurement; please consider this before purchasing Due to monitor display differences, actual item color may vary slightly from images Package Includes: 1 x Step Drill Bit