We purchased Indows for a sleeping porch that is three stories above the ground and set over a steeply slanted roof. The safety and convenience of interior storm windows was our first consideration; second was the wish to maintain the exterior appearance of the original multi-paned lift-out windows. We are completely satisfied with the insulation, noise reduction, and sparkling clarity of the acrylic panels. Our windows are irregular in shape, but the inserts are a perfect fit and nearly invisible when installed. Now our neighbor wants some!