I have purchased two of these cat boxes.  One for my cat & one for a friend.  One of them is hard to put the lid on & off.  It was the 1st one I purchased (for a friend).  The 2nd one I purchased much later goes on & off easily.  I think they may have fixed the problem.  If it wasn't for the problem with the 1st one, I would have rated this 5 stars.  These are soooo much better than the ugly traditional cat boxes. :)