I searched, and tried to get a memory foam. During all purchase process of this item, I was sure that I am buying a memory foam. However, after I got the package, I can not find the "memory foam" such labelling anywhere in the packing box.
I felt I was cheated by the web. it is too big to spend effort to return.
The foam maybe still is made from Polyurethane, but its property is not as good as memory foam.