Sleep Master 13" MyGel iCoil Box Top Hybrid Mattress - King The ultimate Sleep Master mattress designed with the latest comfort innovations, beginning with the MyGel quilted cover. MyGel is an innovative premium memory foam infused with gel. MyGel quilted in the cover of this mattress provides coolness and ultimate sleep comfort. The next layer is an additional 1inch layer of MyGel followed by 2.5 inches of the Pressure Relief Sleep System which gives custom support to key body parts; head, shoulders, and hips, and allows for total relaxation. The HD foam layer and the 7.5 inch iCoil core provide the custom support. The iCoil spring system eliminates virtually all motion transference, and supports the entire body keeping the spine properly aligned.