While this Air Pump utilizes a USB cord for continuous power for normal use, it also features an internal battery that instantly kicks in if power is lost. This keeps your tank’s water safely oxygenated in the event of a power outage in your home! Think of it as a 2-for-1! It’s both a normal air pump that also gets you out of a pinch! It also features a LED battery power display: 4 lights means fully charged and ready to use, up to 13 hours in constant air mode, or 26 hours in Interval mode. Convenient: This Air Pump hooks up to most aquariums by utilizing the metal clip found underneath. It can also be normally placed on a flat surface. Furthermore, the Air Charger I operates at 2.5 Watts, produces between 40 – 43 dB of sound, and pumps at 0.4 Gallons per Minute (G/Min). Included Items: The Cascade Air Charger I comes with the following: Air Tubing (standard size), a USB charger, air stone, and noise absorbent rubber base. please read directions: For optimal performance and longevity, please read and follow directions. Keep the Air Pump above the waterline, and never put it in water. It hangs outside the tank, not inside. Measurements: The body measures 4” (D) x 3” (W) x 1.5” (H) when standing on a flat surface.