The CV4035 is a CV4004 fitted with flying leads rather than pins. Electrically it is a M8137 special quality version of the definitive audio double triode ECC83 (CV492).
This high impedance amplifier triode was designed specifically for audio use and has a high amplification factor of 100.
The two triode sections.
The triodes seen end on.
The thin glass tube envelope is 20 mm in diameter and, excluding the base wires, is 47 mm tall.