Fulfills its function properly!

I've been looking for a way to the external hard drive, carried out their USB powered, can switch off.
My first idea was a USB hub with individually switchable connections.
Although the HUB has its own power supply unit has a data transfer between PC and external HDD is not possible.

Unlike with this switch: The data transfer works well (without any distortion) and when not required, the external hard drive are switched off.

For this task, I see in this switch is the only solution.