The S130 gas filled voltage stabiliser is on a B4 base. The striking voltage is 180 V and the burning current is from 6 to 75 mA. Within the current range the regulation is 5 volts.
The other S130 exhibits in the museum are housed in the earlier balloon envelope.
The thin metal cylinder electrode is ribbed for mechanical rigidity. The top mica holds it firmly in the shoulder of the envelope.
A closer view.
The B4 base and the green printing of the Cossor name and valve identification.
Thanks to Alex Dutton for sending the images.
The balloon envelope is mm in diameter and, excluding the B4 base pins, is mm tall.
References: Data-sheet & 1040. Type S130 was first introduced in 1935. See also1935 adverts.