The new Serta® Sheer Slumber® mattress delivers quality, convenient comfort to your front door in our smallest carton ever. We’ve combined cooling Serta® Gel Memory Foam with our durable Serta® Foam Core for a cool, supportive mattress that keeps you in dream-land all night long. Serta® Gel Memory Foam: "This unique gel memory foam contours to the body for cradling comfort and allows airflow to keep you cool and comfortable throughout the night".