McKesson Seat Back Cushion 16 W X 17 L Inch Foam (1065588_CS) 4/CSErgonomically designed to help keep spine in proper alignment while providing added support and comfort Promotes improved posture for the head, neck and lower back lessening risks of discomfort, pain and injury common when sitting for extended periods of time High density polyurethane foam conforms to provide support to lumbar region. Stabilizing board insert prevents hammocking in sling back wheelchair. Stretch, nylon cover is low shear, breathable