The Aroma Sphere is a perfect entry-level diffuser that is very simple to use. Just add oils or fragrance to the pad and plug in the USB cord (or add batteries) and you have instant aromatherapy. The compact diffuser will cover up to 100 square feet. Run Time: Continuous Operating Modes: Continuous/ Off Light Mode: N/A Power: By AA batteries (not included) or USB cord Coverage: Up to 100 sq. ft Included: 3pc Refill Pad and USB Cord Dimensions: 4 x 4"