Description: This is a portable finger hand-held 4D Usb mini trackball mouse with off-table design for free and comfortable operation. Ideal for laptop users. Features: 1. Off table and without limitation of operational space 2. 4D page scrolling function can be controlled simply by your thumb 3. Features 3-button design with trackball 4. USB 2.0 interface, plug and play, no software required. 5. Special design, can avoid the harm on your wrist and muscle, greatly reduces discomfort for Arthritis and CTS suffers 6. Easy to use - left or right hand, or cradled between both 7. Mini size, light weight, easy to carry 8. Ideal for both laptops and desktops 9. Material: Non-slip soft rubber 10. Place end of index or middle finger on trigger button thumb on roller ball 11. Suitable for Tablet PC Laptop Desktop computer 12. Compatible with Windows 95 version B / 98 / ME / 2000 / XP / NT/WIN7 13. Unit Dimensions: 3.15 x 2.05 x 1.97 inches (8 x 5.2 x 5cm) 14. USB Cord Length: 73inches (186cm)