The ergonomic design of convex and concave，when you lie on your back or side.allowing the cervical spine to be more efficiently supported, stretched and relaxed., Soft and breathable fabric that allows air to circulate through the pillow all night long, skin-friendly materials to keep the pillow cool while you sleep., The sleeping pillow core is made of high-density slow rebound memory foam. moderate hardness and softness, Keeps its shape and firmness for use longer time.,