Designed for Natural, Relaxed Handling, Includes Detachable Wrist Rest, Sensitive Multi-Surface Sensor, Five Programmable Buttons, USB Dongle Included, Connect to 3 Computers at Same Time. The 925 Ergonomic Vertical Wireless Mouse is designed to keep your hand in a more relaxed natural upright position as you click drag and scroll. An included detachable wrist rest provides additional comfort. Designed to reduce muscle activity by 12% the mouse is certified by Human Factors and US Ergonomics. The mouse tracks on practically any surface thanks to a sensitive multi-surfacesensor. Other features include a six-month battery life and five programmable buttons. A USB dongle is included for wireless connectivity and operation. Also this mouse allows you to be connected to three laptops/desktops at the same time over Bluetooth and to switch between them with just a click as needed.