Up for sale is a closely matched pair (2 pieces) of highly sought-after WWII era Sylvania 6F8G / VT-99 dual triode tubes, brand new in their original US Army Signal Corps military contracting boxes . Made in the USA, these military-grade tubes feature iconic black coated glass, durable black bases, top grid caps, and crisp silver military stenciling. Renowned as the sonically superior precursor to the 6SN7, these tubes deliver legendary holographic soundstaging, rich mid-range warmth, and ultra-quiet operation when used with adapters in 6SN7 preamps and driver stages.

As shown, both tubes have been thoroughly tested on our laboratory-grade Amplitrex AT1000 tube tester. Plate current (Ip) and mutual conductance (uMhos) measurements alongside percentage performance ratings relative to nominal specs are detailed in the table below.