The CV264 is a neon Watt-meter. The prototype was the AP1188.
The test is to place the device 2.5 feet away from 18 kV of 90 KHz and at that point the central tube will glow along the whole length. The breakdown voltage must be high as 400 VDC does not initiate any discharge.
The Imperial measurements are 0.25 x 0.5 x 6 inches.
The complete watt-meter complete with end corrosion.
One end, the tube has no conductors within it what looks like a wire is an optical illusion.
The thin glass tube envelope is 6 mm in diameter, and including the end hooks is 148 mm tall.
