The 5U4G rectifier delivers 100 Watts of DC power. It would be used for all types of medium power equipment and was used extensively in 1940's equipment.
The Westinghouse logo of this Canadian valve is clearly seen in the main image. Here one anode is seen face-on.
The top mica components. The two central rods can be seen to connect to the springs that tension the oxide coated ribbon filaments. The working area of each anode is quite small. The flange formed by folding the anode passes round the support strut and the anode can be seen to be stitched together.
The classic envelope is 51 mm in diameter and, excluding the IO base pins, is 118 mm tall.
References: Data-sheet, Data, 1040 & 1043. Type 5U4G was first introduced in 1938. See also1938 adverts.