Note holes 1, 2, 3, and 4 at the bass end and 85, 86, 87, and 88 at the treble end have each directly above them a perpendicular oblong port. These oblong ports are the accordion dynamic control ports and are connected by tubing to the Duo-Art cut-out pouch blocks directly behind the spool box. These blocks contain a series of four pouches on either side of the blocks, one on the bass end and the other on the treble end, and are connected to the supply from the Duo-Art cut-out block on the left-hand end of the spool box; they are marked ''Duo-Art On" and "Duo-Art Off." With the Duo-Art lever at the "On" position, atmosphere is admitted to the top side of the note pouches on the blocks marked 1, 2, 3, 4 notes and 85, 86, 87, 88 notes; this inflates the pouches and cuts off the note holes from the tracker bar. With the Duo-Art switch at the "On" position, atmosphere is admitted through any one of the accordion dynamic control ports above the note ports, passes through the pouch cut-out block, thence to the accordion primary valve box, from there to each of its respective primary valves, then to each of the accordion dynamic pneumatics on the expression box. In the upright model, the dynamic valve box is assembled on the expression box frame. In the grand model, it is attached to the frame of the case as closely as possible.