2X-Office is the name of the device driver that you need to download in order to get the most of your A4Tech mouse (models OP-57D | MOP-70D).
This driver package includes the device drivers for all versions of Windows (9X/ME/NT/2000/XP/Vista) as well as X64 versions.
You must to download and extract the package contents in some area of your hard disk (if you don't have Winzip or something similar, you will need it too). Then remove all previous mouse drivers before installing the new ones.
This package includes some small applications to get the most of your mouse.