The CV4085 is the special quality M8195 version of the EF86 audio voltage amplifier in a UK government Common Valve type code. The CV4086 is the same valve but with flying leads.
The mesh screen covers the inner structure. Note the screening plate below the lower mica.
The suppressor grid wire can be seen through the mesh screen. The vertical lower screen shields grid 1 and grid 2. The heater is wound as a double helix to minimise the external AC hum field.
The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins, is 48 mm tall.
References: Datasheet & 1040. Type CV4085 was first introduced in 1959.
