These underpads were made for air-flow therapy beds. The top sheet is strong and made of soft, cloth-like material. The back sheet is also sturdy and made of non-slip, cloth-like material. This product was designed to allow air-flow when the product is dry, and even when wet! Each underpad has a super absorbent polymer. The reason for this is so that it will direct moisture to a certain area and retain it. This also helps manage and control odor.