Beautyrest 5.5-inch Supreme Gel Memory Foam and Fiber Mattress Topper (King) Measures 5.5 inches thick, 4 inches of gel memory foam plus 1.5 inch fiber filled cover Density: 3.2 pounds Memory foam is resistant to dust mites and is naturally antimicrobial Temperature sensitive foam adjusts to your body temperature Draws uncomfortable warm air away from your body, Fiberfill provides hypoallergenic, down-like comfort