Comprehensive Measures for Unpredictable Situations Dry Run Protection (for 30W only) Prevents the mini aquarium heater from running dry, displays error code (E1) if not fully submerged. Submerge to clear error and resume function. Overheat Protection Stops heating if water temp exceeds 97℉/36℃, displays error code (H1). The betta heater will resume heating once the water temp drops to below 93℉/34℃. Memory Function The mini fish tank heater automatically resumes last temperature setting after power outage, no need to reprogram. Easy to Use Simply press the "SET" button, and the temperature will increase by 1℉. When it reaches 93℉, pressing it again will reset it to 64℉. Indicator Lights The fish heater is equipped with indicator lights. A red light indicates that it is heating, while a green light indicates that it is maintaining the set temperature. Suction Cup For easy placement, the betta fish heater comes with a suction cup. The suction cup can be securely and conveniently attached to the aquarium.