Product review (4 stars): Easy to use.  Cleans up very easily.
My problem is not with boiling over but with, scraps of food or my husbands peanuts dropping down by the burners.  I was constantly having to clean the whole top.  These make it easy.  I would buy them again.  My only suggestion would be to add a small circle in the middle.  I used a tool to measure ECG's to map out the perfect size I wanted.  I don't know if children still have to use protractors but that would work nicely as well.  If you are a perfectionist (guilty), I'd prefer to have the center clearly marked first.