Earls stocks O-ring seals in both the traditional Buna N synthetic rubber and in Viton (R) fluoroelastomer. The Buna compound is compatible with most fuels, hydraulic fluids, and lubricants up to a temperature limit of 275 degrees Fahrenheit. Viton(R) is preferred for synthetic lubricants, oxygen bearing fuels and additives, and non-ether based brake fluids. Viton (R) also has more scuff resistance, a longer service life, and a higher temperature rating of 400 degrees Fahrenheit. Viton (R) is a registered trademark of DuPont Performance Elastomers.