It works by running a version of EFI that lets OS X function on the PC architecture. The EFi- X is composed of an embedded CPU with several gigs of onboard memory, and a USB connector. It features its own firmware, which is constantly being upgraded by the creators to improve features and address any discovered hardware issues. "
Review Link: http://www.testfreaks.com/blog/review/efi-x-usb-v1-reviewed/