Up for sale is an exceptionally rare matched pair (2 Pcs) of vintage NOS GEC ATS25 / ZA3496 heavy-duty power triodes, housed in their original government military boxes. Manufactured in England by General Electric Co. (GEC), these ultra-collectible valves feature robust black plate construction, a vintage leaf getter, high-insulation ceramic bases, and top cap plate connectors. Revered in high-end custom triode amplifier builds for their massive soundstage, exceptional dynamic drive, low noise floor, and legendary British military engineering standards.

Both tubes have been tested on an Amplitrex AT1000 automated valve tester at nominal reference settings. Plate Current (Ip) and Transconductance (uMhos) measurements alongside percentage performance ratings relative to standard factory specs are detailed in the table below.