The IV-15 is the Soviet analog of the popular DM160 / 6977 miniature tuning indicator tube. Like the DM160, the IV-15 does not have a variable length
display, only the brightness can be changed. With an envelope height of
25mm the IV-15 is slightly larger than the DM160, but is still a very tiny device.
Glow color: green
Voltage of filament: 0.6V ... 0.9V
DC grid voltage, min: -2V
DC anode voltage, max: 55V
Current of filament, max: 1mA. 
