EDIT, 10/31/15: still everything below true.  I think I have but two or three of the original set, left.  The rest either melted in the microwave or the tops tore, and I'm not sorry to see them go.  I got Ziplock and Tupperware and plain old (better, actually) Kroger brand to work better.  These all have FLAT tops.  The GLAD bowl design is better, but that top is a killer and too much temptation for me to buy again until the top is fixed.