About this item. High hardness and rust resistance: These hex head taps are made of high speed steel and feature a nitriding surface finish for high hardness and rust resistance. Designed with spiral splines: Taps with drilling function, used for drilling a hole and cutting new threads at the same time, will give you a smooth tapping experience on metal, aluminum plate, iron, etc. More precise and effective: Automatic centering point, does not require auxiliary center drilling and center punching, more accurate, eliminate human error, greatly reduce processing steps and time costs, improve work efficiency. Anti-wear: The back of the cone is covered by the tap to prevent excessive punctures caused by damaged threads. 6 different sizes from M4 M8: Quick change 6.35mm (1/4") hex shank with imperial sizes engraved on the taps to meet your various requirements. See more details.