It can be operated in various ways to long-term use without harm to wrist or muscle No limitation of operational space Avoid sitting closely to the monitor and reduce the harm of radiation and eye fatigue Plug and play ,no software required Fits left and right handed users It is ideal for laptop users. Specifications: Compatible with Windows95/ 98/ 2000/ ME/ XP/ NT Unit Dimensions: 3.15 x 2.05 x 1.97 inches (8 x 5.2 x 5cm) USB Cord Length: 73inches (186cm) Color : Black How to Use:Put your index or middle finger into the hole of this mouse. Control the track ball for moving cursor and the right and left button with your thumb When using ""Drag and Go"" function, the button in the hole of the mouse that has the same function as the left button of the common mouse Use the left button to lock the screen and then you can control the track ball to roll your screen freely Material: PVC silicone Package Includes:1 x Hand Held 4D Usb Mini Trackball Mouse Note:Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.