The Hyde & Sleep Smart Pillow offers the perfect sleep experience no matter what your pillow preference. One side of the pillow offers a combination of memory foam, and a cool to the touch pillow cover. The cover uses technology developed by NASA that manages the heat of the pillow by cooling the fabric when the temperature is hot, and warms the pillow when it is too cold. The technology works by reacting to the skins temperature to ensure optimal levels of thermal comfort. When you flip the pillow over, theres another story The other side of the pillow is filled with ultra fine synthetic fibers, to provide a super soft duck down feel. So if you prefer a softer more marshmallowy feel, you can use the softer side of the Hyde & Sleep pillow! The pillow has been specifically designed to provide neck support and improved spline alignment. Our materials are carefully chosen to ensure maximum breathability, and are well suited to allergy sufferers.