Maker's Name: 
Where made: 

Glass envelope, duodecal base, top cap.

This valve was used in black and white television receivers for horizontal deflection of the electron beam in the cathode ray tube.

This valve and similar ones were replaced by smaller types with double or more the transconductance and half of the anode dissipation requirement. The light staining inside the envelope is barium from the

cathode. This indicated that the volve has worked hard for some time.