Prevue Pet Products Mineral Blocks Bird Toy with Beads and Shapes contain natural ground seashell and limestone grit as an excellent source of calcium. The toy also contain iodized salt, which is a required nutrient for bird health. The Mineral Blocks bird toy is designed for small to medium sized birds. Since this is a handmade item, dimensions may vary slightly. Prevue Hendryx is the leading manufacturer and importer of pet cages in the United States. Pioneering and innovating the pet cage market since 1869, the Chicago-based company is the only U.S. manufacturer to offer a full product line of bird cages, toys and accessories, dog training crates, travel crates, and small animal cages.