(NBR, Buna-N) Nitrile rubber o rings are the most widely used o-ring material in the word. Good watertightness, heat and abrasion resistant, excellent oil resistance, corrosion resistant, high pressure resistant, good mechanical performance, no pollution and abnormal smell.

O rings are widely used by plumbers and DIY homeowners, like:
Seal water pipes
Repair leakage of faucet, sink and filter, etc.

O rings are also widely used by professional mechanics and DIY car owners to fix engine fuel lines leaks, air leaks and other leaks like:
Oil, Coolant, Power steering fluid, etc.
Use for mechanical/grease applications etc.
Used them on hydraulic lines.