ERGONOMIC DESIGN - handheld trackball mouse wireless can greatly avoide the harm of palm and muscle of your wrist for long time using mouse. ATTENTION: IF YOUR MOUSE IS NOT WORKING WHEN YOU WENT A FEW MINUTES WITHOUT USING IT, PLS KINDLY CLICK TO WAKE IT UP.IF STILL NOT WORKING, PLS CHECK BELOW ISSUES: 1, CHANGE BATTERY AND TRY OR 2, TURN IT OFF AND ON OR 3, REMOVE THE USB RECEIVER AND TRY IT. TRACKBALL COMFORT - Ergonomic handheld trackball mouse wireless is a best choose to reduce the chances for Arthritis and suffers. Hold ergonomic handheld trackball mouse wireless in your hand like a trigger and use your thumb to move around. Sculpted shape supports your hand staying in one place, move the cursor without moving your arm.Suitable for both left and right hand - New style, no space limitation, left or right clickers, fit left and right handed users. ADJUSTABLE DPI - ergonomic wireless handheld finger trackball mouse have 800 or 1200 or 1400 or 1600 DPI resolution optical tracking technology that provides higher sensitivity than standard optical mice. handheld trackball mouse wireless have a Sensitive rolling ball and frequency stable 2.4GHz receiver(For wireless mouse, the valid range distance is about 10M, the signal can't go through wall). WIDE APPLICATION - handheld trackball mouse wireless including USB 2.0 interface, plug and play, no software required. Suitable for laptops and desktops, but NOT FOR TABLETS AND CELLPHONES. Compatible with: for XP or VISTA or Win7 or Win10 or Linux or Unix or OS. Wireless mouse, by AAA battery (not included), plug and play. Material: plastic colour: black Package Contents: 1 x Wireless Trackball Mouse 1 x USB Receiver Only the above package content, other products are not included. Note: Light reflection 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. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.