An O-Ring is a torus, or donut shaped seal that is typically used to prevent the leaking of air or fluid in or out of a closed hydraulic system. O-Rings are commonly used as a seal but have been used as drive belt, bumpers, vibration dampeners, decoration, and even as jewelry.
O-Ring seals are commonly made of rubber, but they can also come in Teflon®, Thermoplastic elastomer and Teflon® Encapsulated. There are 36 different types of rubber compounds on the market today, because of the different temperatures, chemical exposures and environments that O-Rings are subjected too. There is no one type of rubber that is compatible with all the environmental conditions. Therefore the need for different kind of rubber and different grades of each rubber are necessary.