Sold as 1 Each. Wireless connectivity: Bluetooth 4.2. Sensor: BlueTrack. Battery life: Up to 12 months typical usage. Dimensions: 1.01'H x 2.37'W x 4.22'D. Scroll type: Buttons with scroll wheel. Wireless frequency: 4.2 GHz. Color: Platinum. Handedness: Ambidextrous. System requirements: Windows 10, Windows 8.1. Bluetooth wireless range: 33'. Battery: 2 x AAA alkaline. Metal wheel for vertical scrolling and wheel button clicking.