The way in this tool works is switching the version of your WarCraft III. It is usefull when you need to use 2 versions for example 1.26a and 1.27b.
You can switch 1.26a version to 1.27b version and viceverse from 1.27b to 1.26a. 😃 How cool is that 😃 you don't need to get 2 warcraft with 2 diferents versions.
You only need to download the file and extract in your warcraft III folder. Then you open the program and choose what version you want to switch.