The Ecological Laboratories Bird Bath Clear (10BBC4) is an effective bird bath cleaner that keeps your birdbaths and pets safe from organic contaminants. Clean hard water stains and crusty white scale deposits, copper and iron. It uses two (2) unique technologies: 1, it helps prevent the buildup of stains and other mineral deposits and 2; it uses bio-enzymatic activity and helps keep the water clear and free from organic debris that can harm your birds, small fishes and/or frogs. This product makes 4 ounces and made from all natural ingredients. It measures 16.1 inch outside diameter with a 14.5 inch inner diameter.