Cotter pins are simple yet essential fasteners used to securely lock nuts, bolts and other mechanical components in place. Typically inserted through a pre-drilled hole and bent back to prevent movement, they provide a reliable, low-cost solution for preventing loosening caused by vibration or load. Mixed cotter pin packs offer a convenient selection of sizes and lengths, making them ideal for maintenance, repair and general workshop use across automotive, agricultural, engineering and DIY applications.