Epson Progression U12 - Manual (Page 126)

6. Thread the cable through the rear clasp on the side of the
subassembly, as shown below. (You may have to fold the
cable as shown.) Then snap the clasp shut.
7. Now you can attach the hard disk drive cable to your drive.
If only one hard disk drive is installed, you can use either of
the two free connectors on the cable. If you just installed the
second hard disk drive, use the remaining free connector.
Installing and Removing Drives 4-23