I love this mattress topper so much. My king mattress has an attached pillow topper, but it’s still very firm. The topper makes it seem like I’m sleeping on a marshmallow (which is a good thing). I unrolled it on my mattress and there was a decent-sized dent that I didn’t think was going to smooth out (as you can see in the photos). However, I let it expand for the full 48 hours as indicated in the instructions, and it’s perfectly smooth now. Someone mentioned that it’s too long on their mattress, and that was the case for me, as well, but it’s not perfectly square and once I turned it, it fit perfectly.