The type 41 is a high gain audio output pentode that is electrically identical to the type 6K6GT. It was designed for single ended or push-pull use in the output stages of domestic equipment.
This exhibit is from Tungsram but made in the USA and so was probably made for them and not by them.
Not much detail to observe.
From the top it can be seen that all of the grids are on copper supports. The cathode tube contains a slip coated heater with a hairpin bend at the top that reveals the bare heater wire. This is a true pentode with three wire grids.
The classic envelope is 38 mm in diameter, and excluding the UX6 base pins is 88 mm tall.
References: Datasheet, 1040 & 1043. Type 41 was first introduced in 1936.