You are buying a set of (3) Inogen BA-400 genuine medical device batteries for use with Inogen G4 and Rove 4. They have low use hours. We purchased them directly from the manufacturer. Don't get duped into purchasing low quality 3rd party or fake batteries. We have a complete device setup available for these batteries, please send message if you are interested in that as well. Manufacturer suggested retail price 408$ each. Please check the listing photos carefully, they are exactly what you are purchasing!