The GL446A from GE is what the Americans call a lighthouse tube because of its appearance. The 2C40 was the successor.
The cathode with its flat top is placed in close proximity to the wire mesh grid, that connects to the middle ring. The anode protrudes down the top glass cylinder and almost touches the grid. This follows the pattern of most high frequency planar triodes. So called because the operating area is all in the one plane and the electrodes have a very small physical separation.
Most of the European devices had co-axial connections unlike the conventional base used by General Electric. The 1951 data book has this listed but later editions do not.
The GE logo
The central ring with mesh grid within.
The original box that was supplied to the US Army Signal Corps.
The Type designation on the base of the box. The box measures 51 mm square and 78 mm tall. Inside the box, the valve was wrapped in a composite paper. This consisted of several layers of soft crepe paper bonded to an outer kraft paper backing.
The widest glass tube of the envelope is 17 mm in diameter and, excluding the IO base pins, is 49 mm tall.