"This modification is available on backs with Knob Release Hardware frame widths up to 24 inches and can accommodate users up to 250 pounds. This modification is available only on flat backs. The IDERF modification will allow slight rotation in
addition to extension. It will absorb shock caused by excessive tone spasticity or by repositioning. It will extend the life of the wheelchair frame and Basic Insert by reducing stress on the backposts. Not Available with backs that are curved by wood. (Curved by Foam and most other back modifications are available)"