Every person's anatomy is slightly different. People have different preferences about the firmness of their pillow. On average, there are 12 major body shifts and 50 movements in head and neck position during sleep. The Mediflow Water Pillow, with its advanced engineering, adapts to different anatomical shapes and sizes and allows you to personalize the level of support you want. It supports the cervical spine ideally. The water pillow is surrounded by an extra soft layer of polyester fill to make it perhaps the most comfortable pillow ever.