A 3d motion type set the image changes as you tilt the cards. Unlike Kellogg's and other cards using this technology there's no danger of cracking. Instead of building the rippled plastic viewer into the card it is included (and present in this set) as a separate piece. THe cards are NM with a note to odd toning on the reverse that is uniform to all the cards and ma be a part of the printing process as the cards are gorgeous and show no signs of staining on the fronts.