It provides transparent whole disk encryption with Pre-Boot authentification for Windows. Also supports MacOS X 10.4 (non-boot disks only).
In 2007 an undocumented feature was publicized that allows the user to set up a secondary password to access the drive
An undocumented encryption bypass feature was found that allowed the drive to be accessed even without the boot-up password . The PGP Corporation said that the feature had been requested by enterprise users and was not a backdoor .