What an awesome well-made product in a humble price! I purchased a King size mattress together with their bed frame. It's been over a week since our family (parent+toddler) have been sleeping on this new mattress and we are extremely satisfied with the quality of sleep were having. Before ordering, we've tried lying down on several premium brands that were over $1,500 at Macy's, but this one has almost similar comfort. I'd highly recommend if you're looking for a firm mattress (level 7 of 1=extremely soft, 10=extremely hard).
For those who wonder about the actual thickness, it is definitely 12" (see photo with the measure). The top layer provides a soft comfortable that absorbs different body curvature while the bottom thick layer well supports major weight and movement. Also, it is delivered in a vacuumed condition which makes easy to transport and store. Overall, I'm very happy and would definitely consider repurchasing in the future!