The XN1 is a cold cathode numerical indicator. The anode is common and the 10 cathodes are formed in the shape of the numerals to be displayed. When the discharge is surrounding a particular cathode the shape is highlighted. The XN1 has flying leads. This exhibit is new old stock and the leads are full length at 40 mm.
Face view showing the top of the cathode stack surrounded by the anode.
The anode is solid at the back and sides but formed of an open mesh at the front.
The thin glass tube envelope is 18 mm in diameter, and excluding the base wires is 45 mm tall.
References: Data-sheet, 1040 & 1043. Type XN1 was first introduced in 1960.