"DuraWrite Virtual Capacity (DVC)"
Want to do this branded trick yourself? Enable full disk compression for the drive (using the "Compress this drive to save disk space" checkbox under disk properties in Windows). All they do is take the "free space" they save from the on-the-fly compression feature of the Sandforce controller and present that as extra free space. i.e.: wrote 40GB of C: data to a 60GB drive, but it compressed to 20GB? You're drive now reports as an 80GB drive, 40GB written and 40GB free space (perhaps more if they automatically assume they'll get compression out of what you might write to the drive...).