In many machines and structures, the cotter pin is a simple-looking part that provides crucial safety. Commonly used with nuts, shaft/hitch pins, and joints, it prevents components from loosening under vibration or long-term operation by inserting through a hole → then splitting the two legs to lock. Don’t underestimate this thin metal pin—without it, an entire assembly can fail in an instant. --- Choose the Right Size for Reliable Retention Selecting a cotter pin mainly dep