Thank you RainThat comment is correct. Western Digital's Passport external drives have, for some time, only had a single USB connection on the internal drive's PCB. If you remove the 2.5" drive from the enclosure, it still needs to be hooked up via USB; there is not a SATA header on the drive. There is no "USB to SATA" adapter to remove; it is all built into the drive's PCB, unfortunately.