Penn Plax Air Pod Aquarium Air Pump For Power Outage Automatic Turn On Keeps Fish Safe Up to 55 Gallons Aquarium air pump runs on 4D batteries when it senses that electrical current is interrupted. It will switch from electric to battery operated automatically. Pump is designed for ultra-quiet operation. Pump will only operate when power is out and provides continuous aeration of your tank. Fish need a constant supply of oxygen for survival. An electrical power outage is life threatening. Pump has an adjustable flow control dial with dual air outlets to customize your air flow according to your needs. A handy power indicator light helps to identify which power source is being used. Aquarium air pump is safe to use in tanks up to 55 gallons and can provide power for 150 hours. Larger tanks would require more than one unit. Air pump uses 110 volt electrical current. Air tubing and stone are included for easy set up. A check value is recommended but not included in the kit. Pump is safe for both freshwater and marine environments.