e SATA is the name of the standard for external SATA. The standard is the same as for the SATA that you normally use to connect the hard disks inside the computer, but the e SATA variant gives you the option of connecting units externally, e.g. external hard disks. This means that an external hard disk can use the SATA default & its high speed rather than e.g. being connected via the slower USB (Universal Serial Bus) standard. If you have a SATA port on your computer but not an e SATA port, you can use this adapter in front of your SATA port on the back of your computer as an e SATA port, allowing you to connect e SATA units at full speed.