I was astounded at how much it improved the comfort of my mattress. I recently purchased a queen plush pillow top mattress that was not very plush or felt like a brand name pillow top. Instead of returning the mattress, I searched Great Bay and discovered this. I'm so glad I ordered this one. It does not become flat or need to be fluffed, and it does not move (straps are held to the mattress). If you want to improve a new mattress or even transform an old one, this is the solution.