The CV455 is a VHF double triode, useful for RF stages, oscillators and frequency multipliers. The commercial type designation is ECC81. The American 12AT7 was the prototype.
The anode is made of pressed sheet as normal, the short side is open for half the height and the electrode structure is visible. The anode box is 3 mm deep 10 mm wide and 10 mm high.
The thin glass tube envelope is 21 mm in diameter and, excluding the B9A base pins, is 47 mm tall.
References: Datasheet & 1040.