Add to cart Nova – 3″ CONVOLUTED “EGG CRATE” SEAT/BACK FOAM CUSH(FLEECE COVER) $37.99 3 Foam cushion for 18 x 16 wheelchair – with cover. This cushion (2658-3) provides support and pressure relief. The convoluted foam improves weight distribution and air circulation. It has removable, machine washable polyester/cotton with a fleece topping for added comfort, as well as a 3″ seat cushion with connected 2″ thick back, which fits most chairs and wheelchairs. The weight capacity for this cushion is 250 lb.