METRIC (Coarse and Fine) Chrome Alloy Hand Taps Angle of thread is 60. The crest is flat and the thread has clearance at the root allowing external thread and internal thread to engage well. Larger root radius and lower thread height enable easy screw thread processing and increase thread screw strength. The major diameter of external thread and pitch are specified by a simple numerical value (most commonly measured in millimeters). Taper Taps have a lead of eight threads and are used as a starting tap in difficult or high precision holes. Manufactured from premium chrome alloy steel this general purpose tap is designed for use in medium tensile materials and is for hand or general machine use.