Beautiful 1948 Selmer Super Action (SBA) alto, recently overhauled.
I presume this is a vintage relacquer, very nice kind of honey colour. New chocolate roo pads.
The SBA was introduced as a follow on to the balanced action. It has a neck designed to be slightly brighter and the more comfortable offset right hand stack keys. Apparently some of these made during or just after WWII had black key touches instead of mother of pearl. this one has a black G# key touch, the rest are normal white MOP.
This was the forerunner to the MKVI so is a kind of transition between BA and Mark VI. A very highly sought after instrument.