The CV4002 is the flying lead version of the CV4014. Electrically it is an M8083 or 6064. These are both designations for the special quality version of the EF91 (CV138).
The special quality version has a more rugged build than the EF91 and was designed for operation in areas of vibration especially aircraft.
The silvering inside the glass is present to prevent the emission of secondary electrons. The Brimar EF91 looks the same.
As the anode is a present as two side plates joined by a strap the grids are easily seen.
The thin glass tube envelope is 18 mm in diameter and, excluding the B7G base pins, is 47 mm tall.
Reference: Data-sheet. Type CV4002 was first introduced in 1953. See also1953 adverts.
