The AirPod® w/Battery Back-Up is a powerful and versitile air pump that can aerate your aquarium while giving you peace of mind. This new state-of-the-art design provides superior power and dependability running continuously on 110V power, and has an automatic battery powered back-up system in in the event of any power loss. Acoustically designed for smooth, ultra-quiet operation, the AirPod® w/Battery Back-Up provides enough air for most aquariums up to 55 gallons in size and features an adjustable flow control dial, a power indicator light, and dual air outlets so you can easily configure any needed air lines. The Air Pod® will operate continuously powering all your aerating needs using your 110VAC power source and will automatically switch to battery power if there is any interuption to the normal power. Perfect for winter outages or transporting fish, the AirPod® w/Battery Back-Up requires 4 Alkaline "D" batteries (not included) that can provide full power for up to 150 hours depending on the life of your batteries. Length of operation with battery power will vary depending on the quality and age of the batteries used. Measures 6.5"x 6.25"x 2" high and has a 6" power cord for easy placement.