The external Hang on Box by Finnex is a must have multifunctional aquarium add-on for those with limited space. This space saving design provides a clear observation area for your intended purposes. All accessories, including a Finnex P-2000 air pump and air line, are include to get the system of your choice up and running out of the box. The box may be used as a quarantine area for sick or fish needing a quite zone to re-coupe. The lower flow gives fish a stable environment without giving them much stress. Ideal for both fresh and saltwater aquariums, some may use it to selective breed their most prized shrimps and fish. Or, simply use it to house a betta, without having a bulky housing taking up space inside your aquarium. Remove the removable baffles for additional space and attach any clip light to have your refugium thriving. The multifunctional box can be used as a refugium filtration system where pods and cheato can further cycle one's aquarium as well as lowering nitrates. Specifications Dimensions: 10.25" x 5.5 x 5 Flow Rate w/ Air Pump: 4.15-4.9 GPH Gallons: 1 Gallon.