A semi-fender washer is a type of washer that has a slightly larger outer diameter than a standard flat washer, but not as large as a full fender washer. This allows it to provide some additional load-spreading and prevent the fastener from sinking into the material being fastened. Semi-fender washers are commonly used in applications where a moderate level of load-spreading is needed, such as in construction, machinery, and automotive components. They are available in various sizes and materials.