The Mullard M8212 is a miniature all glass premium quality pair of signal diodes The CV version was the CV4007. The design was for detector service in wide band equipment. This would typically be RADAR. The premium version is designed to be used in areas of shock and vibration such as aircraft equipment. The domestic version of these diodes was the EB91 and here the use was television video detector.
This professional design is in a reduced height envelope, some 10 mm shorter than the EB91 and much more rugged.
The two diodes are completely separate flat structures separated by a flat metal screen.
The two diode sections with the electrostatic screen in the centre.
The direct equivalence with the CV4007 is shown by the valve having both Type designations present.
The thin glass tube envelope is 18 mm in diameter, and excluding the B7G base pins is 37 mm tall.