Ideal for interior and minimal exterior use, High Resiliency foam is a high quality, yellow, 2.5 ounce polyurethane foam that is wrapped in a thin polyester layer. HR foam is made to sustain shape and quality for years to come. The most reliable choice to ensure you get the longest use out of your custom cushion! If using for outdoors, it is best to keep your cushions clean and dry to prolong insert life.