Aqueon pro aquarium heaters are built to deliver consistent heat. Each unit is made with a durable thermal plastic shatterproof housing and equipped with an electronic thermostat. The thermostat has an auto shut off safety feature, when the top of the heater tilts below the bottom of the heater, it will shut off. Additional features include adjustable heat settings and LED heating indicator that illuminates when actively heating. The suction cups make horizontal or vertical installation quick and easy. Pro Heaters are fully submersible and made for use in freshwater and saltwater aquariums. Available in five sizes to accommodate various aquarium sizes. Aqueon products offers a wide range of items so that you can build and maintain a healthy aquatic environment. All the essentials from fish tanks, filters, lighting, food, care, and other supplies that your pet fish needs. We make it easy for you to get your first aquarium and to grow in the hobby as you become more of a fish expert with every step you take and every new thing you learn. Adjustable heat setting 68 to 88?F, electronic thermostat accurate to +/- 1? shatterproof and nearly indestructible fully submersible; auto shut-off when over-heats, resets when it cools down led light is red when actively heating. For fresh and saltwater aquariums includes suction cups for installation and placement. Recommended for aquariums up to 100 gallons.