1/Memory foam has a perfect curve design which live up to human body engineering principle.2/The pillow case can be removed and washed by hand or washing machine.3/Whether lying on the side or on the back, the flexible memory foam conforms to the shape of your head and neck to keep the spine and back aligned properly.4/The surface of the memory pillow is covered with environmentally friendly gel, which is soft, cool, compression resistant, non-toxic and odorless and gives a cool and comfortable feeling.