The flapper valve is one of the 3 most important parts in an oil less air compressor. The other 2 being the piston cup and cylinder sleeve. The flapper valves, if not made properly will not seal correctly or will tear causing premature compressor failure. They MUST be made from Swedish stainless steel flapper valve material. Only 2 types of material exist that meet our standards for flapper valves. We bring this material into the US them stamp and tumble finish the edges to provide a strong, long life flapper valve.