Porthole Designs

[bgadow]

I recall seeing an ad for a Zenith porthole that had a switch on the front that automatically changed the size; I'm not sure how common the feature was. Then there was the Westinghouse that had a mechanically adjustable mask-I'm not sure if there was a switch for the size to go with it or if you just adjusted the height. Every porthole advertisement I've seen showed a full-view round picture.