Textured Liner. HIGH DENSITY POLYETHYLENE (HDPE) Poly-America offers High Density Polyethylene (HDPE) smooth geomembranes in thicknesses of .5, .75, 1.0, 1.5, 2.0 and 2.5 mm (20, 30, 40, 60, 80 and 100 mils). Rolls are 23 feet wide and vary in length depending on the thickness of the geomembrane. Poly-Flex HDPE liners are the ideal choice for