We use a minimum of 3 lb density memory foam in all of our mattresses and toppers. The rebound is much quicker, which means you can change positions with ease and not feel “stuck.” Our memory foam is not affected by changes in temperature. You do not have to wait for your body temperature to “warm” the mattress up, so it will not be firmer in a cooler room and softer in a warmer room. It will have a consistent feel no matter the room temperature.