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 from water such as tin, ammonia and nitrates. These impurities are usually passed out through urine, and when grass comes in contact with these elements it results in urine burn on grass, resulting in a dead, yellow patch on your lawn. Dog Rocks are a mineralised rock which when placed in a dog's water bowl changes the Nitrogen levels of a dog's urine, meaning it won't stain grass. The key element in Dog Rocks is Zeolite, which neutralises Nitrogen levels without altering the pH level of the water. This is important as a change in pH level can affect a dog's health. Zeolite is often used in aquariums to filter out ammonia and nitrates from the water.