Buna-N O-rings (also known as NBR or Nitrile O-rings) are the most popular and widely used o-ring material because of its low cost, good mechanical performance with resistance to water, most basic oils, lubricants and some fuels, many pneumatic, and hydraulic systems. Buna-N O-rings function well in applications that have limited temperature and resistance requirements. Generally, O-rings commonly provide a pressure and fluid seal between cylindrically shaped, overlapping mating surfaces and are commonly used for engines, faucets, flanges, valves, and various cylinders. Avoid: Sunlight, UV light, ozone and general outdoor weathering or hash chemicals, acids, keytones and many others.