Material: HNBR - Hydrogenated Nitrile Coating: None Material Description: HNBR provides excellent abrasion and cut resistance. It works well with Air, Engine Oil, Diesel Fuel, Hydraulic Oil and Automatic Transmission Fluid applications. Some formulas may be used with Coolant/Urea. Do not use with Biodiesel. Inside Diameter (in): 0.53 Cross Section Diameter (in): 0.09