Serta has created iComfort Hybrid Mattresses that combine the best of Coil support systems with the best cooling Memory Foam, featuring Serta® Balanced Support Foam, Air Support™ Foam and Carbon Fiber Memory Foam. By inserting Carbon Fibers within the Memory Foam, heat is channeled away from your body while the Memory Foam provides exceptional strength for your back and neck support. An advanced Individually Wrapped Coil system adapts to your body for ultimate support and durability. These coils are encases in a dense foam for added edge strength and greater mattress surface use. What makes these mattresses the ultimate in sleeping cooler is the Max Cold™ Cover and the UltraCold System™, giving you an instant, cool to the touch sleeping surface. The iComfort CF4000 Hybrid Firm Mattress is ideal for a stomach or back sleeper.