The Mazda original code was the 6/30L2 but here Mazda use the Mullard ECC804 as the Type designation. The design is a general purpose double triode with a screen between the sections. The main application is in television receivers.
The triodes lie in the same plane with the screen between them.
UK manufacture and a member of the BVA. The grid can be seen to be wound on copper supports.
The control grid wires can be seen to pass flat across the anode.
The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins is 48 mm tall.