It is a kids cardboard picture book that each time you turn the page all the objects are in a different shades of a single color and one object is of a different color. There are words on the pages like rhymes that highlight the object that is of a different color (for example a gray umbrella among a bunch of yellow items). The title might have rainbow in it. On the cover I think there are circle cutouts that get wider and wider that hint at the colors featured.