Got this about a month ago, but just now put on my bed.  We have about a 10" mattress and it fits great, but with the elastic band around the bottom, it would fit fine on a mattress 3-4" deeper, but also 3-4" thinner.  And, unlike some mattress pads I've bought that are smaller on the surface, this pad actually covers the whole mattress top (Cal King mattress).  It's thick, soft and waterproof (yes, we poured water on it to test it).   My only concern is the elastic band around the bottom... only time will tell how long it will retain its shape.  So far, it's an excellent product.