Sterling Seal ORBN037x10 Number-037 Standard O-Ring, Buna Nitrile Rubber, 70 Durometer Hardness, 2-1/2" ID, 2-5/8" OD (Pack of 10) For use across a wide temperature range from -30 degrees F to 250 degrees F, Good/Excellent resistance to many petroleum oils/greases, hydraulic fluids, alcohol, mineral oil and grease Oil resistant applications of all types. Low temperature military uses. Off-road equipment. Automotive, marine, aircraft fuel systems. 70 Durometer 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