For sale is matched pair of 5R4GY rectifier tubes, 2 tubes selected with the same or very close plate current. 

Rebranded Zaerix, they look exact like MARCONI/Fivre 5R4GY tubes.

Tubes NOS/NIB, never used, Tubes and boxes look impeccable.

Zaerix was the brand name of a company called Z and I Aero Services, an important suppliers to government and military contracts.  They did not make valves themselves but they did source high quality valves from manufacturers around the world and ensured they met their high standards.

In photo can be seen example of data results from tests, a pair with around 125% for each of the 4 plate currents, where 100% is 100mA. Heather current was measured to be in range and reverse test diode was made at 300V.

All tubes are tested and each plate indicates over 100% plate current.

5R4GY is equivalent with 5R4, CV10330, 5R4WGA, 5R4GYA.