The reason I needed a new bed was my old mattress had a hump in the middle and 2 sunken areas on each side where my husband and I slept. I put this one on my existing box spring which is split down the middle and either this bed is instantly sinking or the box spring is making it feel like it has a hump in the middle. I suspect the latter, so i may need to buy a new frame if i decide to keep the mattress which is an expense i was not expecting since the site stayed you can put it on a boxspring. This mattress also feels too firm for me and I’m getting some hip pain (side sleeper, 120 lbs) so the jury is out.