Otto the liner is multi-layered. Heres a blurb from there website about it...
-"PPL-24® is a 24 mil (24 thousandths of an inch) thick Reinforced Polyethylene (RPE). It is a "5 layer" construction consisting of 3 layers of LDPE (Low Density Polyethylene) coatings sandwiching 2 layers of HDPE (High Density Polyethylene) reinforcing scrim. This method of construction results in an incredibly puncture and tear resistant lightweight liner material. To our knowledge, the PPL-24 is the strongest RPE available today, and Bend Tarp & Liner, Inc. is the nation's sole source for this product. PPL-24 was originated, developed, and popularized in a team effort by Bend Tarp and Liner, Inc. and Matai, Inc. USA, beginning in the 1980's."
-It feels like the stuff a large rubber raft is made out of. The material is pretty stiff.
-Yeah they have install guys but there expensive.
-There pricing is on there website at
http://www.btlliners.com