The actual sources vary. The EPN valve is a top quality one. I run them myself in all of my engines.
I haven't found a problem with them yet but never say never I suppose?
Most sub-contractors are not in the US. Some previous locations are Israel and Argentina.
The EPN company is currently Ted Standhope who is in Washington. He repackages valves that come from a company located in Las Vegas. I don't know if they manufacture there or if the buy from overseas manufacturers.
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