Add additional comfort to your seating with our 20 x 18 in. Canvas Spa Sunbrella® seat cushion. This seat cushion features a tapered shape with a 2.5 in. cushion thickness. The interior consists of 50% Urethane foam and 50% Polyester fiber wrapped with premium 100% solution-dyed acrylic Sunbrella® fabric. Sunbrella® is a customer favorite because of its durability and low maintenance care. This high performance fabric is constructed to be UV resistant, fade resistant, mold and mildew resistant, spill-proof, and stain-resistant to ensure great quality over time. Secure this seat cushion to your chair with the two ties to keep firmly in place.