For less experienced users an important note: if you 'naked' 3.5-inch hard drives want to connect to a notebook, this cable will not be enough, since it gets only 5V power supply from the USB port, not the needed 12V.
3.5 inch hard drives need but usually + 5V and + 12V. Hence the manufacturers Note: "A power supply is not included; please use the ports on your desktop computer."