The Market St Series is the first step up in our Ultimate Luxury line of mattresses. The Market St Extra Firm uses the same Individually pocketed innerspring unit, which provides for optimum support, while still allowing for excellent contouring, and virtually no motion or bounciness. A layer of Plant Based Memory Foam provides additional contouring and pressure point relief. The Outlast cooling fabric provides for a more temperature regulated sleep, and the 360 degree foam encased edge support makes for a stiff seating edge and reduces roll off.