Sterling Seal & Supply Buna-n O-Rings are the most common and the simplest types of seal with an excellent sealing property and durability Recommended for use with crude oil, gasoline, propane, petroleum oils and water Tube fittings and adapters are supplied with 90 durometer hard nitrile (Buna-N) these O-Rings are well suited for most industrial hydraulic and pneumatic systems They have high extrusion resistance making them suitable for very high pressure static applications Nitrile O-Rings are used as a face to face gasket Style seal or as a shaft seal, and allow both rotary and linear movement Use 90 durometer hard O-Rings for applications with 1500 psi or higher pressures Like their 70 durometer counterpart, 90 durometer nitrile O-Rings are comprised of a Multi-Purpose rubber compound, Acrylonitrile and butadiene that performs well in most environments As with other nitrile O-Rings, 90 durometer nitrile O-Rings resist wear, feature good mechanical properties in Comparison to other elastomers and are built to withstand fuel, oil and other fluids Operating temperature range is -40° to +250F° the 90 durometer hardness of the O-Rings in this Kit also makes them more resistant to extrusion while reducing their flexibility in low temperatures