O-Rings are produced in different materials and hardnesses. The appropriate selection of o-ring material depends on the temperature and pressure of the chemical load. O-rings made of polyurethane are suitable for mineral hydraulic oils, mineral motor and transmission oils, gasoline, diesel, lubricating greases, aliphatic hydrocarbons. O-rings made of fluoro-rubber are suitable for mineral oil environments, have good resistance to ozone and chemicals, aromatic and aliphatic hydrocarbons and minimal gas permeability.