I have been looking at these foam mattress toppers for a year and finally decided that it was worth it to try one rather than buy a new mattress. It came tightly wrapped in plastic and I unwound it on the floor and let it sit as the instructions stated for 24 hours.One of the main things I noticed was there was "no smell" to this product. I have a keen sense of smell and would not be able to use it if there was a chemical smell on it. We put it on our king size bed under the fitted mattress cover and it fit fine. It made our bed seems much higher but the sheets fit too.After the first night I felt an amazing difference when I woke up. Being skeptical, I waited for another night to see if my husband felt the way I did. We both agreed that we were waking up without the usual back aches and pains we had been experiencing. We both are sleeping better and waking up refreshed after a good nights sleep.We are thrilled with it and highly recommend this mattress topper to anyone!