The CD12 is a large numeric cold cathode indicator tube. Each digit is formed from a metal shape and the display is formed by the discharge around the shape. Pin 12 connects to the common anode and each cathode has a separate pin.
The brand name is Rodan.
The cathode stack with the mesh anode above.
Top view with the anode grid and cathodes below.
Each electrode is spaced with a ceramic washer.
The wide glass tube envelope is 50 mm in diameter, and excluding the base pins is 61 mm tall.