CROSS-COMPUTER CONTROL - Game-changing capacity to navigate seamlessly on three computers. DUAL CONNECTIVITY - Use with up to three Windows or Mac computers and laptops via included Unifying receiver or Bluetooth Smart wireless technology WORKS ANYWHERE - 4000-dpi Darkfield sensor tracks flawlessly virtually anywhere, even on glass HYPER-FAST SCROLLING - Scroll through long documents or web pages faster and easier. Or press the wheel and shift to click-to-click mode for precise navigation RECHARGABLE BATTERY - Up to 70 days of power on a single charge, and one minute of charging gives you up to one hour of use; Battery: rechargeable Li-Po (500 mAh) battery.