First introduced in mid thirties
In a way there were 3 versions of the balanced Action
22000's........ Inline action with adjusting screws to adust the Middle D a slightly suspect note on the early Selmers, They also had two separate low B & Bb guards on the bell.. The bell was inline as was on most traditional saxophones at the time.
25000's....... Bell slightly offset with one piece guard on the Bell keys.
27000,s.......The Classic and much sort after model from 1939 which ceased production at the begining of the 2nd world war, and was resumed after the war until the advent of the Super Action. Due to to short supply of mother pearl some of these models had black finger .............