These will make whatever mattress you have feel like heaven.  They don’t go really flat. I put two of them on our mattress and every time we come home from a trip (involving even the best hotels and the mattresses they brag about), as soon as we are finally in our OWN bed, my husband breathes out a big “aaaaaahhhhh!” We actually miss our own mattress and bedding!! [Just another helpful tip—I also layored  a 2” temporpedic mattress topper UNDER the mattress pads, but it wasn’t until I found these pads and double-layered them on that we REALLY experienced that wonderful “aaaahhh” feeling, and if you do this you must always use extra deep-pocket fitted sheets, but it’s worth that little extra effort because these mattress pads maintain their “lift” even after washing and drying—in fact they’re BETTER after washing and drying!!