This heater is built with shatter-resistant quartz glass and is designed to sit fully submerged in an aquarium, mounted vertically or horizontally using the included suction cups. The internal thermostat is factory calibrated to hold water near 78 degrees Fahrenheit, within about one degree, which suits most tropical community fish. An automatic safety shut-off feature helps prevent damage from overheating, and a built-in LED indicator glows red whenever the unit is actively warming the water. No dials or settings need to be configured before use, making setup straightforward for both new and experienced fish keepers. Suction cups are included for mounting inside the tank. Room temperature and tank size can influence how often the heater cycles on to maintain the target temperature.