Wouldn't be so unpleasant sitting in a hard surface while relaxing outdoor? You can either buy a new chair with soft and comfortable cushion on it or use an outdoor cushion. Replacing new cushion on your old seat and any outdoor chair would also be a good solution if you want to save. So, what kind of foam and cushion you would probably buy and best for outdoor use. Dryfast foams are suited for outdoor use where moisture and precipitation like rain is prevalent, such as in patio furniture, including under Phifertex material, or in marine cushioning on personal watercraft. Reading reviews online and asking the sales representative are good options in buying quality product that you need. Click on the link provided for product details and information.