"The Seagate FreeAgent 1TB External hard drive has three different ways that it is able to connect to your computer, which makes this external hard drive very versatile between different setups and can be maximized for data transfer speeds. The three interfaces that it takes advantage of are USB 2.0, FireWire 400, and eSATA. The USB 2.0 and eSATA connections are located on the USB/eSATA module that is already installed on the bottom of the FreeAgent, however if you wish to use FireWire 400, you will need to remove the USB/eSATA module and install the FireWire module, which is very easy. The modules are held in by one screw, which upon removal are able to be popped out."