General description Spiral Groove Step Drill Bit Set features a unique trapezoidal structure that allows one drill to create a variety of openings. This set is designed for use on wood, metal, and stainless steel, making it versatile for different applications. The drill bits are titanium coated for enhanced durability and performance. Technical specifications Material: Stainless steel high speed Package includes: 3 drill heads, 1 tool bag Recommended drill speed: 250 to 400 rpm Usage These drill bits are designed to create clean openings without the need to use the center of the head, reducing the risk of breakage compared to ordinary twist drill bits. For optimal performance, injecting water to cool the drills during use can prolong their service life.