Safely increase the water temperature in your small glass or acrylic marine or tropical aquarium by a few degrees. The compact Hydor Mini Heater features a small, flat, space-saving design that lets it hide discreetly in small tanks and bowls. Itís completely submersible and safe to use if left running dry. Can raise the temperature as much as 5 degrees Fahrenheit with no danger of overheating. Can also warm plant roots in small aquariums. UL-listed. Includes 77-inch power cord.