The Sierra Sleep by Ashley MyGel Hybrid 1100 Memory Foam 11 in. Mattress combines memory foam with a traditional innerspring core - it's the best of both worlds. This mattress also extends upon the memory foam revolution with the thermal comfort of cooling gel. Gel-infused memory foam conforms to you to provide luxurious support while allowing body heat to dissipate. Deeper down, this mattress features a base layer of high-density foam topping a bed of individually wrapped coils. The washable knit cover is easy to remove. A foundation or box springs is not included.