... input device in today's world market,,which combines the 2.4GHz wireless radio frequency,optical trackball,two mouse keys and scroll wheel ... Keyboards Keyboard Dimensions :360*160*35 mm Net weight :540g 2.4G Wireless Technology ,Intelligent Frequency Hopping Technology Working Rangy: 10-15 ... buttons ,1 scroll wheel USB Receiver Nano Receiver .Plug & forgets 2.4GHZ Wireless multimedia trackball keyboard