Circlips are available in two main types which are external circlips or internal circlips, (they can also be referred to as retaining rings). External circlips are a type of fastener which look like flexible, open-ended rings and are usually made from stainless steel.
External circlips are designed to fit tightly around a shaft. External circlips can be chosen to replace threaded sleeves, rivets, cotter pins, set collars, nuts, machined shoulders and similar bulky fastening devices and they come in both metric and imperial sizes.
Circlips also have a smooth side and a rough side and it is important that the clip should be installed with the smooth side facing the part and the rough side facing outwards in order to help prevent damage.
When measuring the size of an external circlip, you should measure the nominal size of the groove diameter. Do not measure the shaft diameter as this will result in an inaccurate measurement when comparing external circlip sizes.
External circlips are designed to fit around a bore and internal clips are made to sit inside a cylindrical shaft or housing.