Each pillow starts with a 100% soft cotton casing and is then filled our Deluxe Cluster Fiber. This is a hypoallergenic and machine-washable polyester fiber that is a soft fill but structured to be enormously supportive.
This is the top-of-the-line product in polyester fibers and far exceeds downs, feather and micro-downs in support. What sets it apart is the fact that, in one sense, it is already clumped or matted into tiny clusters which means it will never clump or mat again. You'll never end up with a worn-out solid mass of fill in your pillow. The pre-clustered nature of the fill also means that there is a "mechanical spring" already built into each cluster that provides the support. Given that this is a loose fill material, you are even able to adjust the pillow and have it conform to your bends and curves without it going flat.