Thank you very much for viewing. The button battery is already installed. Monotaro LED Light Magnifier Thin Portable Lens Size 70 x 50mm Presbyopia Features: Thin type convenient for carrying. You can choose from 3 magnifications depending on the application. With LED light for bright viewing. Applications: Measurement, inspection, etc. Caution: *Do not use for purposes other than the intended use. *Press the orange button after inserting the batteries to turn on the light. Press again to turn off the light. Magnification (x): 3, 5, 7 Material (Body): ABS Type: Portable Material (Case): PVC Lens Size (mm): 70 x 50 Batteries used: CR2032 x 2 (sold separately) Continuous lighting time: Approximately 10 hours Material (Lens): Acrylic #Magnifier