Update, June 2016. The mattresses have finally broken and aren't comfortable due to the deep "divot" that occurs where we sleep, despite regular rotation. Two years is honestly a decent length of time for these mattresses given the price, I don't know what I was saying originally about 5-6 years. We've now flipped them over to the "hard" bottom with a 3" latex topper on top and it's awesome, believe it or not. I actually may prefer the "hard" side vs the intended sleep surface! Fingers crossed we'll get another 1-2 years out of them now on the reverse side.
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Original review: We did not want to wrestle another king mattress into our bedroom and wanted to try foam vs springs. These were a great option although the original shipment came as Twins, not Twin XL's and had to be reshipped. Twin XL's are a fantastic option vs a King, and we use a 3" topper and don't even notice a gap. At this price if we get 5-6 years out of them we'll be very happy.