The GNP-7AH is a cold cathode numerical indicator tube with a clear envelope. There is one anode and seperate cathodes for each numeral. The numerals are stacked and shaped in the form of the number. The orange neon discharge glows round the shape of the wire and thus forms the indication.
Seen from the side the anode is an open hexagonal lattice with the stacked cathodes enclosed within.
The front view.
Thanks to David Knight G3YNH for the data-sheet.
The thin glass tube envelope is 18 mm in diameter, and excluding the base wires is 44 mm tall.