The CV449 is a small, special quality voltage stabiliser. The striking voltage is 115 Volts and the maintaining voltage is 85 Volts. For a tube current variation of 1 mA to 10 mA the voltage regulation is 4 Volts.
This valve would have been used to directly stabilise the voltage for an oscillator or be employed as a voltage reference for a stabilised supply. In the latter case the tube would be operated at constant current.