External retaining rings, also known as "external snap rings", are essential mechanical fasteners that secure shafts in position by fitting snugly into machined grooves on the shaft's exterior surface.

These versatile components are widely utilized across various industries including automotive manufacturing, military and aerospace equipment as well as in medical devices and other industries. Installation and removal of these rings requires specialized tools called snap ring pliers, which are designed to safely compress and expand the ring without damaging its structural integrity or the shaft surface.