I Have slept on 15 mattresses in 15 months. The two twin Xl Green Sleep Niu's purchased from Soma in June of 2014 are the least comfortable. I contacted Soma in Nov of 2015 ( Illness intervened) because the Green Sleep mattresses are 3 inches wider than frames purchased earlier from Soma and were supposed to be o.k for the Niu's. the mattresses sag and I can feel springs when I sleep on my side. . The only solutions offered by Soma would have cost us more money so I gave up in March of this year.