Gel Memory Foam Twin Mattress Topper

I purchased this for my uncomfortable Helix mattress. The worst mattress I ever owned. I'm a large woman so Helix was supposed to be for heavier ppl. It was too soft and very difficult to turn in. I'm a side sleeper only and I was waking up with shoulder, hip and leg pains. I couldn't afford another mattress so I thought a mattress topper would help. I knew I had to let it decompress for at least 24 hrs first, and I only have one bed so I had to place it in the spare room on some plastic storage bends under it. According to the instructions here and on the Novella website it says to decompress for 24 hrs, but the instructions from the box says 48hrs. I believe 24 hrs to decompress and 48hrs to air out the chemical smell which I hardly could smell. I seen after 16 hrs it was at 3.5". After leaving out for 30 hrs it was still 3.5". I knew that was as high as it was going to get. I seen a lot of ppl here upset saying theirs compressed only up to 2" or 3" for a 4" topper. In my opinion they were sent a 2" or 3" instead of a 4". That is sad considering you will NOT get this topper back in the box. There is no wheres on the topper or the box stating the size or height. I worried that would happen to me, but I was ok with 3.5". I still would have been happier if it was the height they stated. It fit my full sized mattress perfectly. First I just placed the sheets on top of it and it kept moving side to side which was really annoying me constantly having to get up and reposition it. Then I put my purple mattress protector over it which is thin and fits very tight on the bed with extra big pockets and the topper hasn't moved since. so if yours is moving, you will need a snug mattress protector on it. I highly recommend purple, which is water proof and thin. I sleep soo good on this. No shoulder pain or any pains at all. The amazing thing is how easy I can turn around on it, much easier then my helix mattress alone. This provided just the right firmness I needed to make up for the soft mattress. Lets see how it does with time. So far I'm very happy with this.