The CV4031 is a special quality version of the 6J6 double triode and also has the designations 6101 and 6J6WA. This valve was developed for industrial and military applications from the CV858.
The copper grid supports and flat U channel anodes are arranged either side of the flat central cathode.
The construction in more detail. The separation between the grid wires and the cathode is very small and demands precision at all stages of production.
The thin glass tube envelope is 18 mm in diameter, and excluding the B7G base pins is 44 mm tall.
Reference: Data-sheet. Type CV4031 was first introduced in 1963. See also1963 adverts.