The spacer layer 34 is preferably formed of a flexible material such as PP or PVC while the bottom layer 36 is preferably formed of a sheet of woven nylon 38 with an interior coating 40 of PP or PVC, as shown in FIG. 4C. A top layer 42 of the wrap portion 12, is coupled to the spacer layer 34 and the bottom layer 36 so that the inflation chamber 28 is formed between the spacer layer 34 and the top