This pond liner features a 14 mil thickness, reinforced PE outer layer, and an HDPE middle layer, reducing water leaks for long-term outdoor use. Four metal Buttonholes make installation simple—just lay the pond liner in place and secure it where needed. Ideal for ponds with plants and aquatic life. | Vevor | | 20 x 25 ft Pond Liner, 14 Mil Thickness, 3-Layer Reinforced PE Fish Koi Pond Liner for Outdoor Ponds, with Hemmed Edge | Black | Best Buy