This is a portable finger hand-held 4D Usb mini trackball mouse with off-table design for free and comfortable operation. It is ideal for laptop users. Descriptions: It can be operated in various ways to ensure 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 Compatible with Windows95/ 98/ 2000/ ME/ XP/ NT