I got this mattress to replace an ancient mattress.  We let it inflate outside, so it would be easier to carry inside.  It inflated instantly!  We are very happy with the size of this mattress; 9 inches works just fine and is actually just a bit higher than the old one.  Our dog is  having to get used to climbing onto a higher bed.  I wanted a hybrid mattress, memory foam for my husband's bad back, and cooling.  It hits all the marks.  My husband has had much less pain and is sleeping better, and he's finding it comfortable.  Our dog approves.  I could sleep on a cement floor, so this is luxury to me.  No need to pay more.