Sterling Seal ORBN238x10 O-Ring, Number-238 Standard, Good/Excellent Resistance to Many Petroleum Oils/Greases, Hydraulic Fluids, Alcohol, Buna Nitrile Rubber, 3-1/2" ID, 3-3/4" OD (Pack of 10) Sterling Seal Buna N "O" Rings are used across a wide temperature range from -30 degrees F (-34 degrees C) to 250 degrees F (121 degrees C) Buna N "O" rings are used for Oil resistant applications of all types. For example; Low temperature military uses. Off-road equipment, Automotive, marine, and aircraft fuel systems Sterling Seal Buna N "O" Rings are compatible with Aliphatic Hydrocarbons (propane, butane, petroleum oil, mineral oils and greases, diesel fuel and fuel oil) Buna N or Nitrile have good mechanical properties when compared with other elastomers and high wear resistance Buna N "O" rings are not Compatible with product fuels with a high aromatic content; aromatic hydrocarbons (benzene); Chlorinated hydrocarbons (Trichloroethylene)