ACCESSORIES A) Rigid Stiffener Post - Required for panel runs of 15' or more. B) Wall Fasteners - Securely fastens panel to wall. Set of 4. C) Slide-N-Catch Service Window - Slide up to open. Locks closed. 21"H opening with stationary shelves. Price does not include panel. D) Spano-Panel - Adjusts from 2 1/2" to 12" widths between panels or panel and wall. E) Corner Posts - One post required for every 90 degree corner.