They are made on original Philips Heerlen tooling and they have passed strict quality control for export under Philips, Siemens, Telefunken and Valvo brands.
All tubes are carefully tested on calibrated Metrix U61-B tester.
See also my other auctions and visit my eBay store for more vintage tubes and tube parts. More than 200000 tubes in stock and more than 30 years in tube business.