Dog Rocks are a 100% natural Australian product that will save your lawn from those nasty burn patches that your dog's urine can cause. Dog Rocks filter out impurities, such as tin, ammonia and nitrates, from your pet's water. These impurities are usually passed out through urine resulting in urine burn on the grass. Dog Rocks give your four legged friend a cleaner source of water while eliminating those dead, yellow patches on your lawn. Without the impurities in the water, Dog Rocks actually help your dog fertilize your lawn! This is great for you, your dog & your lawn!