Date: 1932. Image by VintageSax
Instrument is silverplated, and has rolled tone holes. This is a transitional model to the 6M.
What Conn said in 1931:
"King of saxophones"
In orchestras or bands, on the stage or in the ballroom, over the radio or in the orchestra pit, there you will find this superb instrument playing a leading role. It is truly the King of the Saxophones. The Eb alto is one of the original saxophones invented by Sax, but the alto, as made today by Conn, far surpasses the original model, due to fundemental improvements in design, bore, tone hole location and key mechanism. Among these improvements are the Hydraulic Expansion Process which ensures a glassy-smooth inside surface, tone hole sockets pulled integral from the body metal and rolled, improved pads and knurled tuning device. These are exclusive Conn improvements and are found on no other saxophone. That is why the Conn alto saxophone is the choice of a host of the world's greatest saxophone artists.