Purchased this for our 9 month firm sealy mattress. Had a very soft mattress before this one and it was too soft! I have bad upper back and neck issues and thought an extra firm mattress would help. At first I loved it but then realized it was adding to my issues and it was too late to return or exchange it. So at 5 in the morning after waking up in excruciating pain, I purchased this topper. I was hoping it wasn't too soft and almost cancelled and got the 3 inch. But am I so happy I didn't! This is absolutely amazing. I still feel like I have the support of my firm mattress with the softness of the topper to add cushion and help my neck and shoulders relax when I sleep. I still have pain when I wake up, no mattress topper takes away bone spurs and hurnaited discs, but it's significantly less. I also find myself waking up less at night tossing and turning, and I was able to return an expensive contoured neck pillow that wasn't doing much either. You will not be disappointed with this purchase. A good nights sleep is too precious to miss out on!