Detailed Product Description numeric keypad1>Asynchronous Design: Allows Notebook User to Enter Numeric Letters and Alphabet Letters Asynchronously. 2>Extra "Backspace" key. 3>Come With 2 Additional USB Port. 4>Plug and play 5>Compatible with IBM compatible PC ,Windows 98, 2000, NT, XP ,Vista 6>Size:12.4*8.5*1.5cm