This cushion is excellent for preventing bedsores. It has a dual structure of urethane and gel. The size is 40.6cm x 45.7cm (as stated in the seller's catalog). Please note that there is some yellowing in the gel part inside, but there are no noticeable stains on the outer cover. Also, this product does not come with the box shown in the photo. This is a great deal, as the regular price is around 80,000 yen.