The Vevor king size mattress topper combines memory foam and fiber fill to add plush comfort and supportive pressure relief to your bed. Its 4" design includes cooling gel-infused material to help manage heat and moisture for a more comfortable night's sleep. The topper is ergonomically designed to contour to the body and support natural spinal alignment. A detachable, machine-washable layer and bedside pocket add convenience for everyday use. Elastic straps help keep the topper securely in place on mattresses from 8" to 21" high.