We bought the Sealy Posturpedic Silver Chill, firm. This mattress is so comfortable to sleep on whether you sleep on you back stomach or side. It doesn't move when one of us gets in or out of the bed, so we don't wake each other up. The mattress is designed to work with a box spring or adjustable base. We chose the box spring. It sat a little taller on our bed frame (which holds the box spring 1 foot off the floor) than we anticipated, but we weren't interested in an adjustable base. I would highly recommend this mattress. No more back ache or stiff joints in the morning.