The Zinus Spa Sensations 4 Inch Cooling Gel Memory Foam Mattress Topper combines memory foam comfort with high-density support for pressure relief and durability. Its dual layers include 2 inches of cooling gel memory foam and 2 inches of high-density base support. Certified for quality, it comes with a worry-free 5-year warranty and is smartly shipped for convenience. Please open your gel mattress topper package within 72 hours of receipt and allow 48 hours for your new mattress topper to return to its original, plush shape.