My Spring Air Comfort Flex "Ellison" mattress was a warranty replacement for another Spring Air mattress that failed. After only 3 months of use, my new Spring Air mattress "Ellison" has failed in the same way that the original mattress failed. It is sagging in the middle, and I can see dips in the mattress. I am not an overweight person by any means, and have never had a problem with other brands. I toss and turn all night and wake up exhausted. This mattress does not have a pillow top, and I was told that I don't need to turn or flip the mattress. I have turned and flipped the mattress anyway in an attempt to get some relief and get a good nights sleep. So far, no luck. I have considered buying a mattress topper, but I don't think that will solve the problem. I suppose I could go back to the store and get yet another new Spring Air mattress because I am still under warranty, but I think I will just pay for a new mattress and purchase a different brand this time.