We sleep on a Tempurpedic bed that is quite firm.  We went on a cruise recently and I loved the feeling of "sinking" down into the bed but still having firm support beneath.  I bought this hoping to achieve the same "feel"…and it worked!  I was concerned that the topper might shift because there were no straps to secure it to the mattress.  But, I placed it directly on the mattress and put the mattress cover over it and it has not moved at all.  I was afraid it would get "flattened" after sleeping on it, but so far, that has not happened.  I am very happy with this product.