DUX Xleep is yet another DUX innovation. The inner core contains a system of active micro springs to ensure that the neck and head stay aligned with the spine. The spring system allows the down pillow to retain its original shape and elasticity year after year, and to feel extra cool and comfortable. The core is encased in a down filled, removable cover that can be washed and replaced, if necessary, which is especially helpful for people with allergies. The DUX Xleep pillow is an experience that we highly recommend.