The DL96 is an audio output valve from Mullard's low consumption dry battery valves from 1954. The audio output is low at 0.2 Watts but considering the low filament power it is quite remarkable.
The DL96 ia a Mullard valve made in Holland and this exhibit is marked Foreign Made and reflects a time when this was to imply an inferior item to a British made product.
The anode is bright as the power is low and the supports for the three wire grids are clearly seen as is the filament connection above the top mica.
The anode side view.
The space above the top mica. The suppressor grid wire can be seen attached to the support. The screen grid wire is much thinner. The control grid support shows the close spacing of the notches.
The base. Although not seen in the image the filament connects to both base pins below the bottom mica, thus the coated filament has two strands passing through the grids. The three part base pin is seen clearly.
The thin glass tube envelope is 17 mm in diameter and, excluding the B7G base pins, is 48 mm tall.
References: Datasheet & 1040. Type DL96 was first introduced in 1953.