Sensor technology: Logitech Advanced Optical Tracking; Nominal value: 400 dpi; Max value: Up to 2000; Number of buttons: 5 (Left/Right-click, Back/Forward, Scroll-wheel with middle click); Weight: 145 g; Battery type: 1 x AA battery (included); Battery life with USB Receiver: up to 24-month; Battery life with Bluetooth: up to 20-month;