Luuf Cooling Comfort Medium 13" Hybrid California King Mattress balances pressure-relieving memory foam with supportive polyurethane layers to deliver a medium, comfort-forward sleep surface. A cooling cover and breathable hybrid build help manage temperature so you wake up feeling refreshed. Made in the USA and shipped as a bed in a box, this mattress includes a 10 year warranty and works with a box spring or foundation to provide consistent support for nightly recovery.