Oil Seal normally consists of three basic components: the rubber sealing element, the metal insert (case) and the garter spring. The purpose of the sealing element is to stop the fluid from leaking between the shaft and housing. The metal insert will give rigidity and strength to the seal while it is being held in the bore or recessed groove. The garter spring will help make the rubber sealing element more effective.

In precision bearings, oil seal helps prevent lubricants from escaping the bearings or a specific area. In machine components, oil seal helps prevent abrasives, corrosive moisture and other harmful contaminants from entering machinery. It also helps stop mixture of two different mediums, such as lubricating oil and water.