|The post card and the image above I think originate in the New York Public Library. They are all over on line so I do not know who to correctly recognize as the originating source.|
|Mine, missing some chrome.|
I thought I may be able to differentiate between Master and Champion by the pull tab on the type slug access door. Then I found some sites with Underwood Master shown without the pull tab. I'm sure there are variations between model years, and maybe even production runs. I'm wondering whether mine is a Master, as I found M to designate that, or was the space bar changed some time in its life, or is that normal for the Master to have CHAMPION on the space bar. Remember in all the typing contests Underwood won.