An early "Victrola" attachment to adapt your existing phonograph to "the RCA Victor system of recorded music" as RCA officially referred to the 45. This type changes records SLAM! BANG! in one revolution of the platter.
In this front corner view you can see the reject button (left) and the power switch with its fairly useless volume control, which was eliminated from the next generation of 45 attachments.
Thanks goes toRoss Rianfor restoration of this turntable.