The Adesso Imouse S8 - Usb Retractable Mini Mouse Is The Perfect Travel Companion While On The Road, And The Perfect Desktop Mouse When You Return, Our Innovative Design Features A Built-In Scroll Wheel To Enable You To Scroll Up Or Down With Pinpoint Accuracy And Control. A Retractable Usb Cable Allows You To Expand And Collapse The Cable For Improved Mobility. Its Built-In Dpi Of 800/1200/1600 And Optical Sensor Lets You Navigate Your Cursor With Better Speed, Accuracy, And Reliability On Almost All Surfaces.