The Cunningham C-300 is equivalent to the UV200 made by General Electric and Westinghouse. The electrode mounting also follows the pattern of the earlier VT-14.
The envelope is clear glass as this is a soft valve with argon gas inside at a low pressure.
The brass base cap and stub pins for the bayonet base.
The C-300 box. The trading as line that was present on the C-301 box has gone. The logo is clear on the box together with the stylised lettering for the Cunningham name. At this stage Cunningham were selling valves not making them. The printing clearly states that this valve was made by General Electric.
Thanks to Joe Gruber for sending the images.
The envelope is mm in diameter and, excluding the UV base pins, is mm tall.
Reference: Joe Gruber. Type C-300 was first introduced in 1920. See also1920 adverts.
