Matched Trio Sylvania 12B4 12B4A Vacuum Tubes NOS NIB 6GV5 NOS NIB black and silver bottles and

black and silver bottles and 4-04 188-5 and 1-39 188-4 provenance/date codes

It has a sheet getter

These tubes have crenelated rectangular mica spacers

This new old stock-TESTING matched pair of Sylvania 6F6GT tubes was tested on our Maxi-Matcher -- with 325 volts on the plates and a bias of -36 volts -- for shorts

67 and 71 where minimum (65%) is 46

Matched Trio Sylvania 12B4 12B4A Vacuum Tubes NOS NIB 6GV5 NOS NIB black and silver bottles andThis new old stock, new in box matched trio of Sylvania MANUFACTURED, Emerson BRANDED 12B4A tubes was tested on our Paul Hart calibrated TV7 U for shorts, gas and transconductance. There were no shorts or gas. They measured 44, 44 and 48 where minimum (65%) is 32 and 100% is 49. Wish I could tell you how they sound, but I don't have any equipment that uses these. WE HAVE SCORES OF THOUSANDS OF VACUUM TUBES. IF IT'S NOT LISTED, WE MAY HAVE IT. PLEASE