The CV5843 (commercial 5965) is a purpose designed long life double triode for use where hum, microphony and noise are not important.
It is a special quality double triode designed for use in computer circuits. It will maintain its emission characteristics after long periods where the valve is biased to cut-off. This characteristic equates to use in a bi-stable or flip-flop circuit.
The twin triodes side view.
Etched into the glass is the commercial 5965 and Made in USA.
The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins is 48 mm tall.
Reference: Datasheet. Type CV5843 was first introduced in 1954.