stock tubes in cayin amps

anyone know what make the stock tubes are in all cayin products ,all marked cayin maybe they are cayins own or another manuf,, with cayins logo on them any clues??
emailed vas industries(cayin distributor) with same question ,got reponse the tubes are cayins own,,,
There are Shuguang-Sino, made in China; you can also find them as rebranded Ruby Tubes EL34s. 
Unassuming and cheap tubes; nonetheless, sound pretty good. They are well-balanced with a hint of warmth.