Infused with the heat-capturing gel material, the top memory foam layer is designed to prevent heat build-up. Microscopic gel beads capture heat and move it away from the body to help regulate temperature as you sleep. This surface layer of memory foam has a ventilated design that improves airflow. The open cell structure of LUCID memory foam makes for a longer lasting, more resilient foam that will not leave long-lasting body impressions. Made of a cozy TENCEL blend fabric (10 percent TENCEL lyocell, 90 percent polyester), the soft cover creates a breathable air layer at the top of the mattress.