O-rings/gaskets are the seals that are compressed between the fuel cap and the fuel neck. They help join these surfaces together and prevent leakage of fuel. Keep in mind, just like anything else, o-rings will wear over time, no longer properly seal and need to be replaced.
This is a replacement Buna-N o-ring/gasket (also known as Nitrile or NBR o-ring) for the Leak Defender® fuel cap. We recommend replacing the original o-ring/gasket every 3-5+ years. Different factors such as regional climate (e.g. humidity, temperature, etc.), contact with combustible gases & vapors, how frequently you refuel, etc. Under the proper conditions, they can very well last a lot longer than that, but it’s always a good precaution to have one on hand when needed and to replace ASAP if your noticing any fuel residue or other signs of deterioration.
NOTE: Sold individually, not as a pair.