What is a spanner used for? A wrench or spanner is used to provide grip in applying force to turn or loosen different jobs. They come in different shapes and sizes, depending on the job you need to do. Of the different types of spanner, comination spanners are one of the most common - On one end of this spanner, an open-end spanner, and on the other end ring spanner is made. At both these ends, the spanners are of equal size.