Ideal for medium size ponds, this smartpond® Pond Skins® 13' x 20' pond liner is reinforced with a sturdy but lightweight mesh weave. It is easily manipulated and manageable in all temperatures. Its textured surface promotes beneficial bacteria growth making it safe for fish and plants. The liner is made of 14.5 mil-thick PVC and is puncture- and UV-resistant. A quality liner is critical for the adequate development and dependability of a pond and its components. This product is backed by a 20-year limited warranty.