Multi-line hold function / The mounting direction of the main unit can be placed vertically or horizontally for a clean arrangement. Safety device / Shuts off the power supply when heating in the air (when the safety device is activated). Safe design: The body is made of self-extinguishing resin that does not ignite and the cover is made of aluminum for added safety when empty firing (heating in air). Small heater comes with a ultra-small controller. Set freely from 68°F to 98°F (22°C) with the dial. *There is no function to cool the water temperature. LED indicator/power on status with LED illumination for easy viewing; Compatible water tank quantity: 30 - 60 L; For indoor aquarium; Heater part size: W 6.3 x H 2.4 x D 1.2 inches (16 x 6 x 3.2 cm); Controller part size: W 2.4 x H 1.3 cm