We were skeptical until we tried them. An all-natural solution to the problem of pet urine burn marks on lawns and in back yards, Dog Rocks are hassle free and easy to use. Simply place the rocks in your dog's water bowl, and the problem fades away. Nothing leeches into your pet's water-the rocks purify the water, removing harmful trace elements, and thereby lowering the amount of nitrates that are expelled in the dog's urine. If you find that your dog dislikes having Dog Rocks in his bowl, then store the rocks in a pitcher full of water. Pour your dog's water into his bowl from the pitcher. Thoroughly tested in the gardens of Europe and Australia, more than one million packs of Dog Rocks have already been sold worldwide. Available in a 2-month or 6-month supply. Australia.