Abstract: An improvement to the seat having relatively adjustable sections disclosed and claimed in U.S. Pat. No. 3,749,442 to restrict the movement of each separate seat section to movement only back and forth in a longitudinal rocking motion as opposed to universal movement, to thereby more effectively and efficiently assist in the comfort of the individual and adjustment of the seat to movements of the user without causing undue fatigue over time. The improvement includes a seat rocking member such as a cylindrical rod affixed to the lower portion of each seat half and a pair of spaced apart resilient receiving members for each seat half to movably and rotatably support a seat half on the base of the seat. The resilience of the receiving members permits the the seat rocking members to vertically move downward within the receiving members when a force such as the weight of a person pushes downward on the seat.

Abstract: A seating unit with a flexible seat back having an upper portion separated into two halves positioned to support a user's back at opposite sides of his spine, and with these halves being mounted for resiliently resisted rearward deflection relative to one another in order to accommodate movement of the user's body, and with a slit or the like being provided at the center of the back between these halves to enable projection of the user's spine rearwardly beyond adjacent portions of the user's back for optimum comfort at all times. The back structure may be connected to a generally horizontal seat element, which may be bifurcated to have two relatively movable forwardly projecting portions. The device may also have an anchoring portion for detachable connection to a cushion of an upholstered seat on which the unit is to be used.