[Amoze]

Is this a Mark Vi? The serial number is 28698 which I think puts it in the model range of the balanced action horns

 

[FutureSaxConnoisseur]

It should be a 1939 Balanced Action (based on the SN), the Super Balanced Action didn't start production until 1948, and the Mark VI ~1954
A nice rare, beautiful horn.

 

[TyYez]

It's a BA. IMO BA altos play better than most VIs.

 

[scrollshank]

That's normally called a Balanced Action or BA. The best alto I ever played was a BA that was on consignment at Barnard Repair and in need of an overhaul. I still kick myself for not buying it.

You can check out this video:

Repairman's Quick Overview: Selmer Balanced Action Alto & Tenor Saxophones