The firmness rating for this mattress is very misleading. If you are looking for a springy mattress this will work. But I was looking for a firm mattress that provides good back and neck support. This did not serve this purpose. I would not rate this as a firm mattress by any means. The mattress sinks when you lie on it. So it is not good for someone with a bad back or who needs good back/neck support. 
Having said that the delivery was super fast as was the collection when I requested a return as this mattress did not suit my purpose.