Ergonomic Design for More Comfort: Unique adjustable hinge allows you to customize the trackball angle from 0 to 20 degrees according to your needs, ensuring a more natural, comfortable hand position for all-day comfort | Precise Thumb Mouse: ProtoArc trackball mouse provides accurate and smooth tracking, allowing for easy navigation through documents and web pages. You no longer need to move your arm for the movement of the cursor. Your thumb will control the cursor instead. It will effectively reduce fatigue and strain on your wrist and arm. More productive in the narrow space, such as the messy desktop, couch, bed etc | Bluetooth & 2.4 G Wireless Connection: PLUG and PLAY. This trackball mouse has triple connection modes. You can control three devices at the same time, switch freely between PC, laptop and iPad with just one button to improve your efficiency. Compatible with Windows, Android, Mac OS PC Laptop Desktop etc | Rechargeable & Adjustable DPI: The bluetooth Trackball Mouse built-in rechargeable lithium battery. No need to change batteries. Please remember to turn it off if you do not use it for a long time. 5 DPI levels (200/400/800/1200/1600) allows you to change the cursor sensitivity easily and track more smoothly | Quiet Clicking: Smooth frosted surface and quiet clicks can bring a better user experience and free your worry about bothering others and keep you stay focused while working. Note: The middle scroll wheel is not silent. All the buttons are non-programmable and the back forward buttons are not compatible with Mac OS system