Western Digital’s My Passport Essential SE is currently the only portable external hard drive to boast a whopping 1TB of storage space. Despite this, it is one of the smallest hard drives around and it is quite speedy, too.
For the My Passport Essential SE, Western Digital bypassed the standard SATA II circuitry and built a USB connection directly into the 2.5in internal hard drive, making it shorter than other external hard drives. Unfortunately, the company chose to integrate a micro-USB connection instead of the more common mini-USB port found on external hard drives and digital cameras. While the connection is supposed to be more durable, the cable is also harder to replace if lost.[source]