This genuine Midwest Engine replacement cotter pin can be used in the small engines of outdoor appliances such as lawn mowers, snowblowers, leaf blowers, lawn tractors, and wood-chippers. A cotter pin is one of many kinds of fasteners; its specific function is to ensure that nuts and bolts remain connected to one another. A cotter pin is particularly effective in small engine appliances that vibrate erratically. Though this vibration can shift nuts and bolts and gradually unscrew them over time, a cotter pin will ensure that the nuts and bolts remain in place.Despite the fact that cotter pins are usually a precautionary measure to prevent nuts and bolts from loosening on their own, cotter pins can be subject to damage themselves in the form of cracks, warping, or erosion. This damage can come from overuse, age, exposure to the elements, or collision with a hard surface. In the case that the cotter pin is no longer holding nuts and bolts in place, a replacement should be ordered immediately. Remember to always wear gloves when handling, repairing, and operating outdoor equipment. This cotter pin is compatible with the following brands: Midwest Engine, Snapper, Simplicity, and Murray. Part sold individually.