Logitech Wireless Combo Mk520 With Keyboard and Mouse-(Certified Refurbished) Sleek full-size wireless keyboard with softly rounded keys for hour after hour of typing comfort Contoured invisible optical mouse that tracks on just about any surface, with rubber grips and smooth, accurate cursor control (The optical sensor does not work on glass or mirrors) Virtually no battery changes get up to three years of battery life for the keyboard and eighteen months for the mouse( Keyboard and mouse battery life may vary based on user and computing conditions) Powerful 2.4 GHz wireless and one tiny Logitech Unifying receiver give you a reliable connection without delays or dropouts.