The Two in One has a double electrode structure (filament, control grid and anode). This sample has a nickel base cap and barium gettering.
It is believed that this valve was made by QRS - the company who bought Atlantic and Pacific.
The original box measure 50 mm square and is some 128 mm tall. The identification on the box is a paper label stuck over an earlier design. This suggests that QRS were using up old stock.
Thanks to Joe Gruber for sending the images.
The balloon envelope is 44 mm in diameter and, excluding the UV base pins, is 104 mm tall.
Reference: Joe Gruber. Type Two in One was first introduced in 1919.
Updated August 04, 2020. shape:balloon construction:pinch type:triode age:pre.1920 base:uv pins:4 pin:1.g1 pin:2.f pin:3.f pin:4.a