Conn 18M New Wonder "Series II" Straight Soprano
Date: 1926. Image by VintageSax
Instrument is silverplated. This is the classic straight soprano saxophone, as opposed to the curved soprano. All "New Wonder" saxophones have rolled-tone-holes and "nail-file" G# keys. These days the community calls these the "New Wonder (series) I" or "New Wonder (series) II" saxophones. Conn themselves never referred to these as "New Wonder I" or "New Wonder II" but simply as "New Wonder".
For a thorough review of the 18M New Wonder "series II" straight soprano saxophone, see Thomas Zinnen's discussion here.
In his review, Thomas Zinnen says the sound of this soprano saxophone is "awesome". However, because saxophones built in that era had a different design to modern ones, it absolutely requires a vintage mouthpiece. A modern mouthpiece will not work properly and cause the instrument to be out of tune with itself. Judging by the review, you will have to experiment with mouthpieces until you will find one that works. With my admittedly meager knowledge of saxophones I seem to remember reading somewhere that in those days saxophones were built to take mouthpieces with large chambers, much larger than most modern mouthpieces. That might be an avenue to investigate.
Thomas Zinnen says the keywork doesn't feel very ergonomic and perhaps was designed for someone with small hands. It doesn't have a high F# and no left hand G# to C#/B/Bb activation. Thomas also strongly suggests using a good saxophone technician who knows what he or she is doing with respect to this kind of vintage equipment.