Works great! Easily fits 18 oz Cheerios or 18 oz Corn Flakes. I bought a 21 oz box of Cheerios by mistake; it almost fit, except for one bowlful. These really are air tight. The cereal stays fresh and crunchy down to the last bite. It was a different size, but one of the same models arrived and when I opened it there was a sucking sound almost like when you open a new jar. It maintained whatever different air pressure there was at some previous time until I opened it. Who knows for how long that was, but it was at least overnight because I opened it a day after it arrived. The plastic is sturdy. It's rigid, so it'll probably crack if you drop it any distance, but definitely not from normal use. I stored some homemade soup (mmm...) in another size in the freezer for a month. The soup held very nicely, the surface didn't freezer burn and the plastic behaved well. I have not used in the microwave. The top has a soft seal and I don't know what would happen to it. I've only hand washed. Highly recommend.