Aquascape Non-Woven Geotextile Underlayment Roll is used to protect pond and water feature liner from rocks, roots, and other sharp objects that may damage the liner. The underlayment is lightweight, spreads easily, and has a non-slippery surface, making installation quick and easy. The soft geotextile is made from polypropylene and allows for any gases to escape properly, rather than becoming trapped beneath the liner.