The Lenovo Wireless Mouse N3903 offers exceptional comfort and cordless convenience. It's ergonomic design provides comfort while allowing users the ability to operate with either hand. The integrated on/off button on the bottom of the mouse, allows you to conserve batteries (2 AAA batteries included). Simply plug in the tiny USB nano-receiver and forget it. Get responsive, smooth cursor control with high-definition optical tracking. This mouse will easily operate on wood, carpet, and other difficult surfaces.Metal 3D island&coffee color match ideapad NB style Wireless mice, small size,comfortable & portable Ergonomic design, good touch feeling and quick response Mini dongle fitting in the mouse battery store for ease in travel Easy tracking on carpet,wood and some other difficult surfaces On/off switch self-sleep function for saving energy Strengthen optical system for adapting more kinds of surface