Circlips

The two basic designs circlips come in are external and internal.

External circlips fit around a shaft, pressing on it, whilst internal circlips are fitted inside a cylindrical bore, or housing, and push outwards. 

Circlips fit into a groove on the inside of a bore or the outside of a shaft. They work as a load-bearing shoulder which positions and holds mechanical parts. They provide continuous radial force and are secure against high rotational speeds because they are retained within the groove.