The Sandpaper Refill 4 Sheets is a set of wet-use sandpaper sheets, commonly used in pool and spa maintenance. These sheets are designed to handle tasks like acid washing, removing surface stains or buildup, and smoothing rough concrete or plaster finishes before recoating. Their paper backing allows for flexibility during use, and they are specifically suited for wet sanding applications, which helps reduce wear during prolonged contact with water or damp surfaces. These refills are a practical choice for performing surface prep on pools, spas, or similar wet environments where traditional sandpaper would degrade too quickly.