Two layers of very durable PVC plastic with strong polyester inner mesh between layers of PVC. Liner with two small round holes on the side to attach suction and return fittings. Suction and return fittings included.Specifications:- Approximate set-up size: 4,88 m x 1,22 m- Water capacity (80%): 20 m³- Weight: 67,69 kg- Size of box: 62 x 36 x 116 cm- Pcs on palette 120 x 80 x 180 cm: 3- 40″ cont./pcs: 218/color box