The exterior fabric of Wiggy's is textured, waterproofed 300 denier polyester. It is very similar to corduroy. The padding is Densified Polyester Fiberfill. For years, manufacturers of futons have used this fiberfill construction as their padding. I have found that in a 2" thickness it works so well that it can be used alone in winter conditions. Most winter campers use two foam pads, but with the Wiggy pad one is all you need. The fiber differs from foam in several respects. The fiber is completely unaffected by water and will inflate without a valve. Two 1" web belts are positioned at one end, so you can roll it up tight as possible and cinch it down. The pads are also available as mated sets. Using two separate pads under a mated set of sleeping bags leaves a lot to be desired. They slide away from each person. With the mated set, each side stabilizes the other when movement occurs.