It arrived on a Friday, You are supposed to let them breathe. We did not. As soon as it was out of the packaging it found it's true shape. It is encased in a cover, it is a true mattress. I had been cautioned by friends that I may be getting a "topper" rather than a mattress. With that, I had horror images of just memory foam arriving. Not so. Not even a full week and both of us are sleeping better. His getting up in the middle of the night is not waking me. We are not hot. Back feels better. Hope this lasts.