This CBS 5U4G rectifier tube tested strong in both a tube tester and in an amplifier.

This Chinese 5U4G rectifier tube tested strong in both a tube tester and in an amplifier.  The alignment pin is missing so there is a line drawn on the base of the tube to align it for insertion into the socket.  Priced accordingly.

This pair of Fender GT6L6SV power tubes tested strong in both a tube tester and in an amplifier and they are a close match.  These are also marked as Russia Winged-C tubes (model 6L6GC) and are overprinted with the Fender Groove Tubes marking.  Great sounding tubes!

New in Box Electro-Harmonix 12AX7 Tubes are reliable and make great preamp replacement tubes at a great price.