Spiral design, greatly improve the cutting speed, smooth and delicate surface.Reduce the number of tool changing, improve the machine tool and brake rate.High precision very sharp, wear-resistant,durable.Suitable for iron, cast iron, mould steel, alloy steel, welding steel processing etc. 1.Please allow 1-3mm error due to manual measurement. please make sure you do not mind before you bid.2.The colors may have different as the difference display,please understand.