ERSE (Engineers Researching the Science of Electronics) is a USA company manufacturing premium crossover components.
The Pulse X brand features a metallized Polypropylene film manufactured in the far East with precision, German engineered winding machines. They feature pure copper leads and are RoHs compliant.
ERSE was able to co buy the film in large quantities to be able to supply these great capacitors are a very good price. We use these in all ground circuits and other networks were price is a factor.