Step Drill Bit, 4-20mm Nitriding Black Coted 4241 HSS Spiral Cone Cutting Drill with Triangle Shank for Multi-Functional DIY

• Made of 4241 high speed steel, suitable for hardness 25° or less workpiece material, such as carbon plate, sheet iron, steel plate.
• Titanium nitride coating to reduce friction and effectively extend service life, and step drill also has good corrosion and rust resistance.
• Sizes are laser etched into the metal so they will not wear out even after repeated use, make precise drilling easy.
• The proper drilling speed is 250-400 rpm, akes drilling faster and smoother
• NOTE: Injecting water to cool while working can effectively prolong the service life of the drill bit (drilling steel plate must to cool it).

Feature: - By giving you the right depth to guess from the hole. - For home and industry. - Use tools: pistol drill, bench drill. - When the water is cooled while working, it can effectively extend the service life of the drill bit. - The recommended drilling speed is 250-400 rpm. Specification: Material: High Speed Steel 4241 Surface treatment: Nitriding (black) Handle: triangular handle Size: 4-12mm (4,6,8,10,12mm) weighs 20g 4-20mm (4,6,8,10,12,14,16,18,20mm) weighs 50g Package Content: 1* Spiral Step Drill