Ok, truth be told - you don't HAVE to put beans in them!! Frankly, I use them for refrigerator pickles, and making pickled beets. You could put just about anything in them - oh, and beans, too, I suppose!
I have made this form for quite a while, but recently decided to add the lugs on the side. I personally love this feature because I can use rubber bands or some cord to secure the lid. Now I have a reasonably portable Bean Pot! :-)