Flat Glass Marbles details:Material:Men-made GlassSurface:Tumbled matte finsh.include:1 pound cobalt blue glass beads.Wide application:Glass Beads for Vases can use for vases, parties, courtyard stones, flowerpot coverings,fish tanks, aquariums,home decoration etc.Warm Notes:Please note that these stones size is from 17-21 mm, and their shapes is irregular.Please keep it away from children to avoid children eating by mistake.The first time to use them, please wash away the dirt on them several times due to the transport bump.