This round pool liner pad is designed for 18' above-ground swimming pools to help protect the liner from punctures caused by rocks, roots, glass, and other sharp objects. Made from extra-thick geotextile fabric, it adds cushioning underfoot while also helping block weeds and reduce water contamination. The durable recycled material is built for long service life and supports drainage for a cleaner pool base. It can be trimmed for different pool setups and installs quickly on grass, sand, concrete, or wooden decks.