This Seagate Expansion 2 TB USB 3.0 Desktop External Hard Drive STBV2000100 measures 4-5/8" X 7-1/16" X 1-3/8" thick - big in physical size by today's standard, and it weighs a hefty 1.5 lb. Furthermore, it comes with a corded transformer. A 100-240V 50/60 Hz AC outlet is required. It is definitely not for the travelers. However, its generous capacity of 2 TB makes it ideal for desktop storage. It runs on USB 3.0, which is a major improvement over the older 2.0 version, with transfer speed up to 5 Gigabits/sec, versus 480 Megabits/sec of USB 2.0. Computers with USB 3.0 are still relatively rare, but this Seagate Expansion Hard Drive is backward-compatible to USB 2.0, which is what I got in my HP desktop. This hard drive is plug-N-play. Within seconds after I plugged it in, it was up and running. A USB 3.0 cable is included. It is different in construction from USB 2.0 cables. A tiny blue LED lights up when the connection is made. The actual read/write speed of a hard drive is not the same as the USB transfer speed. I tested this hard drive with a software called DiskBench. The write speed of this Seagate Expansion drive ranges from 103 to 162 Megabytes/second and the read speed from 511 to 616 Megabytes/second, which are decent. I don't have USB 3.0, but I can see the logic of buying a USB 3.0 drive for a computer with USB 2.0, because USB 3.0 will be the standard in a few years. I can't speak to the drive's reliability, but I own two Seagate external hard drives and they have been very reliable.