This exhibit is a mystery and no details can be found for it. The envelope gives a string of patent numbers and the message that the heater must warm-up before applying the DC load.
The list of patents. Note also the locating pip for a bayonet base. This is a relic from the UV base days. The UX4 base is of the push-in type.
The top disc is separated from the cylinder below.
The wide glass tube envelope is 39 mm in diameter, and excluding the UX4 base pins is 84 mm tall.
Updated March 13, 2014. shape:wide.glass.tube construction:glass.foot base:ux4 pins:4 pin: