Onepiece Spiral Step Drill Bit — 4 mm to 12 mm (5-step and 9-step options) Key benefits Faster drilling: the spiral step design speeds cutting and improves chip evacuation, reducing drill time for thin materials. Multi-size convenience: two configurations available — a 9-step version and a 5-step version — both covering 4 mm to 12 mm so you can create multiple hole diameters without changing bits. Versatile material compatibility: designed for cutting holes in sheet metal, steel, and wood, making it practical for workshops, trades, and DIY projects. One-piece construction: single-piece design provides consistent cutting performance and reduces the risk of wobble or misalignment. What this solves Eliminates frequent bit changes by providing several hole sizes in one tool. Speeds up common tasks where multiple hole diameters are needed. Handles mixed-material jobs (metal and wood) with a single bit choice, simplifying tool selection. Key specifications Brand/model: Onepiece spiral step drill bit Available step counts: 9-step and 5-step versions Diameter range: 4 mm to 12 mm (both versions) Intended materials: sheet metal, steel, wood Function: step drill for cutting progressively larger holes Practical applications Electrical and HVAC work: enlarge knockout holes in sheet metal panels or create wiring access for junction boxes. Metal fabrication and maintenance: drill multiple hole sizes for brackets, mounting plates, or light-gauge steel repairs without swapping bits. Carpentry and DIY: form clean, progressive holes in wood for dowels, bushings, or routing starter holes. Usage tips Select the version (5-step or 9-step) that matches how many intermediate diameters you need between 4 mm and 12 mm. Use steady pressure and appropriate drill speed for the material being cut to maintain control and prolong bit usefulness. Clear chips regularly when drilling thicker or denser materials to help maintain cutting performance. This Onepiece spiral step drill bit is a practical, space-saving option for anyone who needs multiple hole sizes between 4 mm and 12 mm in sheet metal, steel, or wood.