These used the superheterodyne principle but were lower cost than earlier products, in an attempt to maintain sales during the onset of the Great Depression.
[1] Armstrong and RCA (under David Sarnoff) had a business and technical relationship, that would last into the 1940s.
In 1928 RCA launched their first AC operated superheterodyne radio, the Radiola 60 ($147 in 1928 dollars).
From 1931 RCA produced a range of small mantel radios called the Superette, which at introduction sold for $57.50 not including the vacuum tubes.
These models are based on the R-7 design but are not called Superette in RCA's literature.