Sterling Seal ORBN437 Number-437 Standard O-Ring, Buna Nitrile Rubber, 6" ID, 6-1/2" OD For use across a wide temperature range from -30 degrees F (-34 degrees C) to 250 degrees F (121 degrees C) Oil resistant applications of all types. Low temperature military uses. Off-road equipment. Automotive, marine, aircraft fuel systems Compatible with Aliphatic Hydrocarbons (propane, butane, petroleum oil, mineral oils and greases, diesel fuel and fuel oil) Not Compatible with product fuels with a high aromatic content; aromatic hydrocarbons (benzene); Chlorinated hydrocarbons (Trichloroethylene) Buna N or Nitrile has good mechanical properties when compared with other elastomers and high wear resistance. Good/Excellent resistance to many petroleum oils/greases, hydraulic fluids, alcohol, mineral oil and grease