The Comfort Plus SI series combines the comfort of a 3-inch air mattress with the support and self-inflating performance of a foam core - without the expected weight penalties. This is made possible by our patent pending Delta Coreâ„¢ technology, which removes the optimal amount of foam without sacrificing support or durability. A luxurious 30D stretch knit fabric is used on top for a soft next-to-skin feeling. Lightweight 30D polyester with extrusion laminated TPU is used on the base.