This new old stock, new in box matched pair of GE-MANUFACTURED 12SN7GTA dual triodes was tested on our Paul Hart-calibrated TV7/U for shorts, gas and transconductance. There were no shorts or gas.
Transconductance measured 82/87 for Tube One and 84/87 for Tube Two (Zenith-LABELED, GE-MANUFACTUREDwhere minimum (65%) is 50/50.
They have gray, ladder plates; crenelated, round top mica spacers with an excised square and circle each, O getters; copper support rods; tall bases and 61-13 188-5 and XX 188-5 date / provenance codes, respectively.
I have played them in my Alan Eaton single-ended 45 amplifier and they sound outstanding. They are nice and quiet when the SACD is paused and have excellent frequency response, sound-staging, and a bright and forward sound with great bass articulation as well.