This 201-A features a three point base as well as a spherical envelope. The J shape glass electrode support is clearly seen.
The anode is made of two flat plates, there are two ladder grids and the filament is twisted. The base shell looks to be nickel.
This design was only made for a short time and consequently is quite rare.
A closer view. The electrodes are spot-welded to the support wires.
The original box.
Thanks to Joe Gruber for sending the images.
The balloon envelope is 57 mm in diameter, and including the base pins is 108 mm tall.
Reference: Joe Gruber.
Updated November 26, 2020. shape:balloon construction:pinch type:triode age:pre.1920 base: pins:3 pin: