The purpose of the toe piston just to the right of the crescendo pedal is to instantly turn on "Full Organ". A second depression returns the registration to whatever it was before (whatever stops and couplers were turned on individually or via the crescendo pedal. The Sforzando Reverse Piston also usually includes a few stops that are not controlled by the crescendo pedal, thus giving a truer ""Full Organ" than the crescendo pedal alone. (Whether this is true on this particular instrument has not yet been determined.)