LLDPE Material: The pond liner is made of LLDPE material, pro-environmentally, sunlight-proof, weather-proof. It can restrain the penetration of harmful substances into the pond and give your fish and plants a secure living environment. 20 Mil Thickness: This small pond liner is strong enough to withstand extreme weather conditions, more durable, tear-proof, and puncture-proof. In addition, good waterproof performance can effectively retain the water in your pond. Flexible & Pliable: The fish pond liner has good flexibility, easy to bend and fold. You can cut it in various shapes to fit all irregular surfaces(e.g., waterfalls). For better flexibility, you are recommended to lay the liner under the sun for 10 to 15 min before use. Aging-proof & Durable: Our waterfall liner is designed with excellent durability, high tensile, and impact strength. The size of 20 ft x 25 ft is ideal for small ponds