Husqvarna 531 12 30-13  Cotter Pin

The Cotter Pin, also known as a Split Pin or Clevis Pin, is a pin passing through a hole to attach two or more parts together. Usually made of metal, this pin fastener with two tines is often bent after installation to keep it in place. While most cotter pins are fairly straight, some are in the shape of an R-Clip or Bow-Tie. For ease of use for the operator, Cotter pins are often used on equipment at points where parts are frequently attached or unattached.