Dog Vitamins & Supplements Prevue Pet beach walk perch is constructed of 100-percent natural ground seashell to provide calcium as they chew. The telescoping diameter provides exercise and the shell pieces provide texture to groom beaks and nails. It includes following ingredients: ground limestone, ground seashell, wheat flour, tapioca flour. Measures 5-inch length by 7/8 to 1-inch width. Comes in small size. Available in sky blue, grass green and natural sand white assorted colors.