The EHEIM Jager Aquarium Thermostat Heater is a high-quality, durable thermostat that is perfect for any home. With its fully submersible design, it is safe to use in either freshwater or marine environments. The dial features a blue background with white numbers, making it easy to read. The on/off indicator light lets you know when the unit is on or off, and the shock resistant and shatter proof glass protects the unit from accidental damage.