Enjoy endless possibilities for restful sleep with Chime Hybrid Firm King Mattress in a Box. Feel the support of a traditional coil mattress which contours to your body for a comforting feel. High density foam provides the firmness you love. Gel memory foam provides restorative support for your lower back. Plus, this mattress arrives in a box for quick and easy set-up. Simply bring it to your room, remove the plastic wrap, and unroll.