Some explanation is needed.
The Model 121 Bb Soprano is the Tipped Bell instrument. The Model 120 Eb alto is the Straight model. As you can see, there isn't a difference in prices between the alto models or soprano models, so it doesn't make too much difference. I *believe* that the curved soprano was Model 119, but I don't have anything that old that can corroborate that data.
Additionally, there was an enamel finish available, *probably* at the same time, with the same color selection and at the same rate as the Conn New Wonder instruments. Quoting myself, from the Conn pages:
CHROME FINISH was the trade name for a colored enamel finish. Available colors were red, white, blue, green, Old Rose ("dark pink") and black. This was available as an add-on for any style of plating for a mere $15 extra, in March 1922 dollars.
POLY-CHROME FINISH was the trade name for the CHROME finish, but with added "beautiful designs on bell or body of flowers, vines, etc. in various colors" and cost $25 extra, in March 1922 dollars.
This finish was brought to my attention by SAXTEK and his beautiful green enamel straight alto. He has an original factory warranty card and the original receipt, so I have no reason to doubt that this is factory original.