This Kensington Orbit Trackball with Scroll Ring combines comfort and scrolling functionality. Fly through websites and documents with the scroll ring. A mouse is not as comfortable or small as this device. Compatible with PC and Mac. Orbit Trackball with Scroll. ORBIT TRACKBALL W/SCROLL RING Kensington Orbit K72337US Black Wired Optical Trackball. Kensington Orbit Trackball Mouse with Scroll Ring K72337US Black Kensington Orbit Optical Trackball Mouse with Scroll Ring, USB Interface, Ambidextrous Design, Model: K72337US.