SERA 100W Aquarium Heater. A high quality heater with a 2 mm glass tube and precision protection circuit. Sera aquarium heaters are very short and are easy to install in small aquariums. The function control (on/off) is achieved by means of a small lamp. 100W Heater Specifications: * Length: 8.7" * Recommended Aquarium Size: 18-26 gal. * Fully Submersible * Includes Protective Grid Guard * 2 Years Manufacturer's Warranty