Dress your lunchbox up for seasons , favorite colors, pets and more! Can't decide on just one? Purchase several and mix and match each day of the week. Remove magnets before washing lunchbox. Made out of synthetic rubber certified safe of toxins (unlike PVC magnets) *If the magnets get wet it can cause the magnetic material to degrade and attach itself to the top of the lunchbox (which is magnetic). This can cause rusting. Making a thick paste of vinegar and baking soda, leaving it on the marks for at least an hour and then scrubbing it off and rinsing will clean the spots.