This program will allow to navigate the file system of FIFA 12 opening each single file.
The package includes Rx3 Master, a tool that opens any rx3 file and shows the textures present in the file, if any, and allows you to modify the images and save the file. File Master also have the function of regenerating the bh files.
My recommandation is that you do not remove or add files to the original big files (though you could, but they are quite big and the access is slow) but rather you can add your own files directly in the proper subfolders of FIFA 12 and the bh regenerator will hide the original files, without removing them, so FIFA 12 will use your new files. Another important thing to know is that rx3 file structure is changed from FIFA 11 to FIFA 12.
Rx3 Master can open both formats but if you try to use an old format for FIFA 12, the game will not recognize it.