I really did not expect to like this b/c we had owned a mattress topper before and it hurt my back. I just assumed that this would be an exaggerated version of one of those. I WAS WRONG! This is the best mattress I have ever slept on! We use it on our Cal King on top of our slatted platform and it is perfect. It is the perfect density and one thing that I love is that if our son or daughter are asleep on it and one of us gets up, they never feel it move! I wish we would have purchased this years ago!