A set of four coasters which form changing moiré patterns when rotated. The best way to see the effect is to put a coaster on the table where it is held in place by its non-slip base. It is then easy to use your fingers to rotate the top part of the coaster to reveal the ever changing patterns. Bought by John Davenport from Grand Illusions in October 2012. Made in China for Kikkerland Design.