Large Index Finger-operated Trackball: Compared with traditional thumb-operated models, ProtoArc EM03 finger-operated trackball mouse for large hands, equipped with a large 44mm trackball, encourages better ergonomics, full arm movements and neutral wrist posture Bluetooth & 2.4G ...Large Index Finger-operated Trackball: Compared with traditional thumb-operated models, ProtoArc EM03 finger-operated trackball mouse for large hands, equipped with a large 44mm trackball, encourages better ergonomics, full arm movements and neutral wrist posture Bluetooth & 2.4G Wireless Connection: PLUG and PLAY. EM03 trackball mouse has triple connection modes. You can control three devices at the same time, switch freely between Android, tablet and Mac with just one button.