Dog Rocks are a completely natural product, mined in Australia and used to help prevent burn patches appearing on your lawn when your loving pet decides its bathroom time. They increase the properties of boron, barium, manganese and strontium while decreasing tin levels in the water. By simply placing Dog Rocks in your pets drinking bowl and covering with no more than 2 litres of water, your pet can help to fertilise your lawn rather than destroy it. Laboratory tested and safe for pets, does not affect the pH of the pets urine.One pack provides a 2 month supply.