LUNA fofo's advanced sensors connect to the FOREO app to measure hydration and provide an overview of your skin’s health. Get the cleansing program for your skin profile and enjoy the personalized, spa-like experience. This is an AAA battery-operated brush, and the instructions for changing it are in the photo and inside the package. MATERIALS: Body-safe silicone & ABS COLOR: Sunflower Yellow SIZE: 70 x 66 x 38mm WEIGHT: 70g BATTERY: 2 AAA batteries USAGE: Up to 400 uses STANDBY: 180 days FREQUENCY: 150 Hz MAX NOISE LEVEL: <50 dB INTERFACE: One button