These dice are made from the same material as the interior of the Faux Metal™ dice we debuted at shows a few years back. This material is about 63% heavier than the normal plastic used by the German factory to make their dice. The advantage of these dice is that they are heavier than normal dice so they have the feel of being special but are not so heavy that they are likely to damage the surface they are being rolled upon. Testing is always recommended, though, as you don't want to dent Aunt Millie's favorite table! We liked these complementary opaque colors because they are bright, unique, and look good. These dice will brighten up any gaming session and will definitely get noticed! We don't think there is anything quite like these presently available at this price point. Please be understanding that there is a minor issue with the material that causes occasional mold marks. We think that the positives ‘outweigh’ this small negative.