If you are looking for firm, this is it! I don’t sink into this mattress at all. The motion isolation is great and the edge support is good. The springs in this mattress are silent. However, i’ve had it for about a week now and the height is no where near 13.5 inches. It is more like 12 if i’m being generous. It also hasn’t expanded fully on the top and bottom edges where it was rolled up so my bed looks higher in the middle than it does on the edges.