The 0B2 is a B7G voltage stabilizer. These devices were made obsolete by the Zener diode.
The regulation of the 0B2 was 3.5 Volts for currents of between 5 and 30 mA. So the voltage across this tube in service would have been held at between 106 and 110 volts. The tube strikes at a voltage of 133 volts.
The construction is of a central rod anode within the outer cathode cylinder. The gas filling was neon.
The valve is also marked as a CV1833 indicating direct equivalence.
The thin glass tube envelope is 18 mm in diameter and, excluding the B7G base pins, is 57 mm tall.
References: Datasheet & 1040. Type 0B2 was first introduced in 1948.