1. The aquarium heater features an externally controlled electronic temperature setting, intelligent frequency conversion technology, and heating efficiency. Equipped with a builtin precision sensor, the threedigit display accurately and realtime shows the aquarium water temperature, with an adjustment accuracy of 0.5°C/1°F. 2. External Temperature Control: The temperature setting range is 18°C–34°C (64°F–93°F) and can be adjusted . When the water temperature falls below the set temperature, the aquarium heater automatically starts heating until the water reaches the desired temperature, maintaining a constant warmth. 3. Automatic Constant Temperature: If the water temperature exceeds 36°C/96°F, the heater automatically shuts off and stops heating. The heater must be fully submerged in water during use. It features an automatic shutoff when out of water, with an antidry design to prevent 'boiling fish' and enhance safety. 4. It can be connected and powered via a USB plug using a mobile phone charger or power bank. Note that the output voltage must be 5V 2A. A DC 5V/2A fastcharging phone adapter is recommended.