(AC Adapter, Battery & Carrying Case) This audiometer is simple, lightweight and durable. The 650AB can be powered by either a standard 9V battery (included) or can be plugged into a wall with an AC adapter (included). Large dials control frequency and decibel levels and toggle switches control power, left/right and pulse/steady tones. The tone button is membrane covered to provide silent operation. Lights indicate tone, patient response and the 650AB has a low battery indicator. 5-year limited manufacturer warranty.