I purchased this topper for our rarely used daybed mattress which I recently noticed is so uncomfortably hard. The topper makes all the difference and now the bed is great.  I would not put it on a soft or even a medium mattress because it is significantly soft and "squishy". I worried from reviews on other gel toppers that it might have a chemical smell (and I am SUPER sensitive to smells) but no smell whatsoever. Great purchase, great product at a great price.