Ulove Black Wireless Ergonomic Handheld 2.4ghz USB 2.0 Optical Trackball Mouse for Windows Xp / Vista / 7 / Mac Os / Android (With Built-in Rechargeable AAA 3a Battery & Multi Dpi) Combining the trackball mouse with optical sensor. It is same as the traditional mouse, convenient for typing. When placed on the desktop, that is, ordinary optical mouse. Ergonomics design, provide long lasting comfort for right and left handed user. Unique shape, adjust your posture freely. Built-in replaceable battery. Need not to worry about the battery because of using external battery. Allow user to place another AAA battery to use the mouse. Wireless handheld mouse with trackball, it is convenient in the narrow space. Hold in hand, thumb roll the trackball and operate easily. Adjust the posture freely, avoid harm of palm joint or muscle Patented optical technology maintains smooth tracking and precision. Convenient for surfing the web, viewing media etc. Four grades of DPI 400, 600, 800 and 1000, factory setting is 400DPI. Each Click Adjust a grade, the light under the scroll wheel will indicate green light for 600 DPI, red light for 800 DPI, red & green light twinkle for 1000 DPI