The 6AL5 miniature all glass envelope houses two separate signal diodes.
The two diodes are completely separate flat structures separated by a flat metal screen. This clearly shows the signal usage, where it is important to keep RF isolation.
These diodes were specifically designed for vision and sound detection in television receivers. Additionally they are recommended for limiting and DC restoration.
Here the diodes are closer to the central screen than in this Brimar 6AL5.
The anode plates are stitched together.
This valve is 18 mm in diameter and 46 mm high excluding the B7G base pins.
References: Data-sheet & 1040. Type 6AL5 was first introduced in 1945. See also 1945 adverts.