ASTM A574 Socket Head Shoulder Bolts, sometimes called stripper bolts or just shoulder bolts, have a smooth shoulder that is larger than the thread diameter, running down the majority of the length of the fastener. The shoulder, having a larger diameter than the threads allows the fastener to be used in rotating applications such as pulley shafts, bearing pins, axles, and pivot points. The thread length is standard for a given diameter. Unlike most fasteners, socket head shoulder bolts are not sized by the thread diameter and length under the head, rather the diameter and length of the shoulder itself. Dimensional specifications are governed by ASME B18.3.