The CV3512 (commercial 5696) is a special quality industrial thyratron. It was designed for relay switching applications particularly in counter circuits and instruments. Typically the anode circuit impedance would be 5,000 Ω.
For insulation the anode lead is sheathed in ceramic down to the base pin.
The thin glass tube envelope is 18 mm in diameter, and excluding the B7G base pins is 38 mm tall.