This kit includes one 45-mil EPDM pond liner and a thick nonwoven underlayment. Start building your pond with reduced water loss and puncture damage. Designed for simple installation and long-term outdoor use, it works well in landscape ponds, backyard ponds, and eco ponds with plants and pond life. | Vevor | | Pond Liner 15 x 20 ft, 45 Mil, EPDM Rubber Fish Koi Pond Liner and Underlayment Combo, Easy to Cut, Durable & Leakproof | Black | Best Buy