Laser Spinner discs, made by Copernicus toys, are holographic stainless steel discs that have a small bump on the bottom. Just spin them with a finger or two and they can go for over five minutes. This design has an array of concentric circles (which means they share the same center, axis or origin with one inside the other) and seem to grow and shrink as they swirl around each other. Diameter = 3 7/8 inches (98 mm).