The Aquatop Floating Glass Thermometer gives you the ability to easily monitor the water temperature in your aquarium. The thermometer is easy to read and has a safe temperature range display which provides the recommended temperature parameters for most tropical fish. The Aquatop Floating Glass Thermometer includes a suction cup mount that securely attaches to any flat glass or acrylic aquarium surface. Features The Thermometer will float if knocked loose by fish, snails, or during routine maintenance; Safe for Fresh or Saltwater use.