For the last three years I rented places for the winter in Kauai and have been running into "pillow top" matresses which are too hot for me to sleep on. I know lots of way to make a matress warmer but I was stumped for weeks on how to make it cooler until I ran across an ad for the cool bed. BINGO! I have a medium under the sheet and under a towel (unless it is really hot) at the edge of the bed. I roll onto it as much as I want to cool down and sleep! I don't put much water in it so it is easier to move (and less likely to pop a cork) but I do get the air out so it does not gurgle. My partner is fine on hot matresses or I would get her one too. It has been great for me for the last three years and I will not be without it.