Cool and Comfy. The Calista Extra Firm mattress collection bears Beautyrest® Pocketed Coil® springs for conforming back support and pressure relief. It keeps you cool throughout the night with SurfaceCool Plus™ Fiber, which dissipates heat away from the sleep surface, helping to achieve and maintain your ideal sleep temperature. Plus, MicroDiamond® Memory Foam wicks heat away from the body to prevent overheating. Set includes Twin XL mattress and foundation.