The THERALUXE HD Black Collection, gives you a long wearing mattress (20 year warranty) designed for comfort, support and durability. The QLX Spring System, of Individually Encase Coils, provides an unprecedented level of deep, body-contouring support. These coils are encased with a high density foam for greater surface use and a firm edge. Layers of long lasting, Superior High Density Foam, create a comfortable sleep surface. HypurGelTM Plush Foam reduces pressure while controlling the temperature for a better nights rest. The Adaptive™ cover lets you sleep dryer and cooler for the most relaxing of sleep. The Sequoia is ideal for a back or side sleeper.