Much Harder - M35 HSS is much harder than HSS 4241, suitable for drilling stainless steel plates and quenching steel plates, iron plates, aluminum, wood. Good Design: Triangular shank fits into the chuck of power tools securely and eliminates slippage. Two flutes design removes chips faster and allows particles to escape easily. Single step drill bit meets all your requirements, 4-32mm M35 HSS with 15 sizes: 4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 24mm, 26mm, 28mm, 30mm, 32mm Slotted tip increases speed. It can automatically deburr holes while drilling to keep the drill bit clean. You can use water to cool it when it is working and it can be used even longer. Product Description High Hardness: Meichoon M35 Cobalt Step Drill Bits are made of high speed steel with cobalt, which provides a long service life. Features: 1. High speed steel for longer service life. 2. Double cutting blades design provides faster and smoother cutting. 3. Advanced double spiral flute design