2x TESLA ECC802S (=E82CC CV3900 5963) lk Telefunken, Same 1982 Codes, 100%/NIB!
These are industrial-grade tubes made for army or aerospace use, and other demanding applications. Both tubes are mint, evidently never used. Boxes were disinfected. Both tubes test as NOS/100%+ 100% gm/S = 1.0 mA/V, 100% Ia = approx.