UNIQUE EDGE CONSTRUCTION – Dura-Beam Air Mattresses are designed with a unique edge construction to withstand the weight of the sleeper without sagging and is 100% more durable, : LUMBAR SUPPORT – Horizontally positioned Dura-Beams provides 50% greater individual strand count for an improved full body support; Fiber-Tech Construction is comprised of thousands of high-strength polyester fibers for amazing durability and strength