Product review (1 stars): Bad packaging
The three came in a box as opposed to an envelope so the about 1" on the long edge is curled and won't lay flat even when placed on a metalic surface.  So when I put them on the vent there was not enough magnetic surface in contact with the vent to adhere and so I had to improvise.  Junk.  No idea how I am going to flaten them out.