These magnets are a very practical application of a magnet that is both printed and has a dry erase film.  The printing and color scheme allowed the persons taking and controlling inventory to quickly discern the status of an item.  The ability to write on the “label” allowed the label to be made specific to the items on the shelves.  The fact that all of this is resident on a magnet allows quick use on the metal shelving.  An elegant application – and simple and inexpensive to do.