Double Heater Module, Rainbow Lifegard. Double capacity module holds heater 22 inches in length. DOES NOT INCLUDE AQUARIUM HEATER. Compression coupling allows easy installation and removal of heater. Accepts 1 inch or 3/4 inch diameter of aquarium heater. Clear cap to view "On" light of heater. Removes unsightly and easily damaged heater from aquarium. Includes 3/4 inch threaded reducer bushings if threaded installation is desired. Filter dimensions 24-3/4-inches tall by 7-inches wide by 4-3/4 inches deep. Accepts up to a 200 watt heater.