They were the low end model for 1935. Designed for apartments and such. The cold control is adjusted with a screwdriver. They're very cool to look at, but flimsy in comparison to all the other models.
I have listings for Balltops in 1935 and 1936 in two sizes. The cold control is indeed only adjustable by screwdriver from inside the cabinet. Besides that, it doesn't have a discreet defrost setting. Definately the low end model.