The De Forest DL-2 is a detector/amplifier triode. Originally released in 1926 with a Bakelite base cap, the Isolantite ceramic base version was released in 1927.
Thanks to Joe Gruber for sending the image.
The wide glass tube envelope is 32 mm in diameter and, excluding the UX4 base pins, is mm tall.
Reference: Bill Condon & Joe Gruber.
Absolute Maximum Operating Conditions¶
Updated September 22, 2020. shape:wide.glass.tube construction:pinch type:triode age:1920.1930 base:ux4 heater:5.0v pins:4 pin: