High Hardness and Rust Resistance: The taps are made of high speed steel and the surface is finished by nitriding for high hardness and rust resistance. Various Sizes: There are a total of 6 different sizes taps from M3 to M10 that you can use to tap different threads. Spiral Flute: The taps are designed with spiral flutes and the chip cleaning process would be better. Function: These are taps with drilling function, used to drill a hole and cut new threads at the same time, you will have a smooth tapping experience with them. These taps are used on a machine to do tapping, usually more accurate because human error is eliminated. Customer Service: Your satisfaction is our priority. Please check the model you need before purchasing our products. If you have any questions about the product size, please feel free to contact us. Our customer service will do our best to give you a satisfactory answer within 24 hours.