FATXplorer automatically saves a backup of the Security Sector of every HDD you open to this folder. They are saved here in case something goes wrong with one of your HDDs and you need to restore the original Security Sector to fix it. Security Sectors are an important part of Xbox 360 HDDs and having a backup is recommended. For more information about Security Sectors, visit this web page: http://fatxplorer.eaton-works.com/security-sector-information/