At first I wanted a memory foam pad, but I found it when they make it the amount of memory material added to the foam is random. This makes the firmness level to be unknown and I didn't want to spend money on something I won't know about. There is also only a few with gel to make it cooler. Never buy a ventilated memory foam. It's basically hollowed out. I finally decided that it would be comfortable to have something like pillows over my bed, so fiber material. And this one is perfect. It's 3" with 1.5" gussets to keep the fiber in the middle. It has an outlining stitch with four vertical stitches. It's better vertical so your spine doesn't go up and down on a horizontal one. I think square would be okay for a thin one like 1.5"
Now when I first got it,I used to sink into it making it quite uncomfortable. However after one night's sleep, the fiber was pressed and compacted due to my weight of 110lbs. So now it's firm and now I don't sink.