It looks like you're asking about a — likely because you see this name in Device Manager , USB Device Tree Viewer , or a similar tool on Windows.
In technical terms, SES is a standard protocol that allows your computer to communicate with the enclosure (the case) of the hard drive, separate from the storage data itself. wd ses device usb
If you do install the driver, it unlocks several specific "enclosure" controls: It looks like you're asking about a —