Metric DIN 1 taper pins solid steel rods that tapers through the length to a smaller diameter at one end. DIN 1 metric taper pins have a taper of 1:50 on diameter wheras standard inchsized taper pins have a taper on diameter of 1:48 . The length of a taper pin does not include the slightly convex ends. For measuring the diameter of a taper pin the large end for inch standard (imperial) is used and at the narrow end for metric DIN 1 taper pins. Taper pins are mostly used to secure two objects together. Since they have wedge shape, taper pins are self-locking as further it is inserted, the tighter the connection. As they are seated a friction force develops along the whole length and diameter of the pin which locks the pin in place.