The GN-5A numerical indicator tube is a cold cathode gas filled design. The base is also marked as CV5351.
The individual digits are made of wire and according to the anode selected to be powered the gas discharge will glow around the shape of the wire anode. The base is a special 12 pin design. The operating voltage is in the order of 200 Volts.
The CV designation.
The mesh anode at the front and shaped wire cathodes stacked up behind.
The wide glass tube envelope is 44 mm in diameter and, excluding the base pins, is 40 mm tall.
