The valve function is to allow combustion mix flow of air and fuel into the combustion chamber and expel the exhaust gasses.
In order to lower the remaining gasses expelled to the environment, the current engines must work with poor fuel mixes that bring higher temperature in the ignition chamber creating a high corrosive environment. Today engine designers also seek to lower the engine weight and components for maximum efficiency. These engines requires the use of special steels and the design of very thin valves.
Moresa intakes valves are manufactured with alloyed steels with carbon and the Moresa exhaust valves are manufactured with a specific material to support very high temperature (up to 800°C / 1472°F).