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What is the largest you can take as carry on? If I were to take frozen sauce, is it considered a liquid? Thanks... [/quote]

The largest cooler you can take as carry-on must conform to the carry-on size restrictions imposed by the airline you are flying. For most US based carriers it's something like 22"x14"x9".

Any frozen item that in it's normal unfrozen state that is a liquid or gel will not pass through TSA. Thus, frozen sauce, won't cut it.