Date: 1929. Owned by and picture courtesy of Rob Verdi: Saxophobia.net
Between 1928 and 1930 Conn made a somewhat unusual instrument called a Conn-O-Sax. Research indicates it was introduced in the Fall 1928 issue of Conn's "Musical Truth" magazine. It was keyed in F with a range from low A to High G. Apparently it was an attempt by the Conn company to squeeze some more life out of the diminishing saxophone craze of the 1920's. Some were sold, but it was mostly unsuccesful. The sound (of the instrument pictured above, played by its owner Rob Verdi) sounds (to me) quite mellow. More info can be found here: The Saga of the F Alto Saxophone".
What Conn said:
The Conn-O-Sax is a cross between a sax and the old heckelphone or baritone oboe. It looks like this now almost obsolete instrument, although made of metal instead of wood, and suggests the heckelphone in tone quality. It plays just like any saxophone, sounds a great deal like the saxophone and is played with an ordinary saxophone mouthpiece.