(High Density Reinforce Polyethylene) 100% tested , 30 mills, 40 years, limited warranty, UV Protected, Fish Safe, NSF certified for drinking water & very user friendly. It does not requires underlay for most uses. It is Made in America, under the best quality & environmental standards. We ship directly via FEDEX, UPS. DHL or Other to your door. This is our best seller commercial grade pond liner fit for most uses from ponds & lakes to Mining & infrastructure.