Features:-Portable finger trackball mouse -with off-table design for free and comfortable operation. It is ideal for laptop users.-It can greatly ease the harm of joint or muscle for long time using mouse-Avoid sitting closely to the monitor and reduce the harm of radiation and eye fatigue-Dolphin shape design with left/right clickers fit left and right handed users.-Plug and play no software required-2.4GHz Wireless connectivity with working distance within 32ft (10m)Specifications:Power: With One AAA battery (not included)Compatible with: for Windows 98 2000 XP VISTA wins 7 Linux UNIX OS ect..Resolution: 1000dpiColor: BlackSize: 11*6*5cm/4.3*2.3*1.9inchWireless receiving distance: About 15MHow to Use:1. Put your index or middle finger into the hole of this mouse.2. Control the track ball for moving cursor and press the right and left button with your thumb3. When using 'Drag and Go' function press the button in the hole of the mouse that has the same function as the left button of the common mouse4. Use the left button to lock the screen and then you can control the track ball to roll your screen freelyPackage:1x Wireless Trackball Mouse1x USB Receiver