The Serta Comfort Zone Memory Foam Mattress Topper is quite thin at only 1.5 inches, but if you only need to makes the slightest change to your current bed, then it should be perfect for that.

A measure of how much vibration is transmitted across the mattress; for memory- and latex-foam mattresses ... 1 is very soft and 10 is very firm. The Serta SleepToGo is part of the Mattresses ...