I could only sleep on the mattress for three nights.  When I first laid on it I could tell that the Casper king size mattress was shorter than the normal king size mattress.  Instead of 80" in length, the left side is 79" and the right side is 76".  The mattress is not even square.  It is a trapezoid-shaped mattress.  The edge support is very poor also.  My head rolls off the top edge of the mattress and my feet roll off the bottom edge.  I will be initiating a return.