Effortless Precision Drilling: Engineered with four razor-sharp cutting blades, our step drill bit set delivers swift, vibration-free drilling performance. The advanced geometry slices through steel, aluminum, copper and other rigid materials with surgical precision - like a hot knife through butter Durable High-Speed Steel: Forged from premium high-speed steel (HSS), each bit achieves Rockwell 62-65 hardness for exceptional durability. This industrial-grade composition resists thermal fatigue while maintaining cutting efficiency even under extreme pressure and friction 5 Pcs Step Drill: The comprehensive set covers 90% of common metalworking applications with graduated diameters: 3/16"-1/2" (6 steps), 1/4"-3/4" (9 steps), 3/16"-7/8" (12 steps),1/8"-1/2" (13 steps), 3/16"-1-3/8" (19 steps) Laser Etched Markings: Precise depth indicators at every step level. Professional Storage Solution. Enable instant size identification. Smart Engineering Features. Quick-Change Hex Shank. Spiral Flute Design Easy Organization & Identification: Our step drill bits for metal come with a handy storage case, ensuring effortless organization and portability for all your drilling tasks. Clear size markings on each bit allow for quick identification 5PCS HSS Step Drill Bit Set