I am very disappointed in the Stearns and Foster Lux Estate 16" Medium Euro Pillow top mattress King Prime model. After paying over $4000 for such a mattress and only after 6 months, I would hope that it would at least not sag yet. The center of the mattress is like rolling up on a hill. Both sides of the mattress have indentations where my partner and I sleep. Neither of us is a heavy person. I might expect something like this to happen with a soft mattress, but this one of the reasons that we have selected medium.