The Frigidaire 5304464991 Air Conditioner Accordion Filler Panel Set Cut-To-Fit is a replacement side panel kit designed to close the gaps around compatible window air conditioners. This set includes expandable accordion-style panels that attach to each side of the air conditioner cabinet and can be trimmed to suit different window dimensions. It operates by extending outward to fill open spaces between the unit and the window frame, creating a more complete enclosure around the installation area. Positioned along the sides of the air conditioner during installation, these panels support proper insulation, assist in limiting outside air entry, and provide a neater and more secure window fit during regular operation.