Prevail Night Time Disposable Underpads 23" x 36." Available in a variety of sizes and absorbencies, Underpads are designed to protect beds, chairs and other surfaces. All Prevail Underpads feature an Integra Mat or bonded construction that reduces top sheet separation and clumping. For added comfort and skin health, all of Prevail Underpads also feature a soft, yet strong cloth-like top sheet with a flat seal around the pad there are no plastic edges exposed to the skin.