Comprehensive Measures for Unforeseen Circumstances Dry Run Protection (for 30W only) Prevents the betta tank 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 nano aquarium heater will resume heating once the water temp drops to below 93℉/34℃. Memory Function The mini betta heater automatically resumes last temperature setting after power outage, no need to reprogram. User-Friendly Operation Simple Setup 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 mini aquarium 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 small fish tank heater comes with a suction cup. The suction cup can be securely and conveniently attached to the aquarium.