The "B" suffix on this instrument indicates that there are two instruments with the same serial number. The second one is designated as "B" so as not to confuse them.
The interesting thing about the example above is that there are actually three of them.
All three of the saxes with this serial number are Silver Plated Sopranos.
The "original" 9105 (which does not, to my knowledge, have any suffix) had a gold-washed bell interior and was sold to a store in Ludwigshafen, a town in southern Germany.
9105 B was originally sold to Rauber Freres, based in Montreux, Switzerland. They were the swiss distributor for Selmer and later became known as Selmer Montreux.
9105 C had a gold-wash bell, but also had two optional trill keys (Mi and So) It was originally shipped to Frankfurt.
Several years later, when a duplication occurred, the second instrument would be given the suffix "A" in the archives, rather than "B" like this example ... but the suffix was rarely applied to the instrument itself.
stay away from these unless you just want 'em for their collectible value. They're just not near as good of players as the later horns, and the keywork is not as nice as modern horns. Note that early Modele 26 horns often did not have the alt Front F key. This one doesn't and as is often the case, pics are taken at angles that just -happen- to hide the lack of the high F key. I've seen this done many, many times...