Active VGA port replicator.

This active distributor is in good order. Comes with a USB cable for the power, at least provide enough voltage to power the second port. The USB cable is for my taste a little short, it requires to have a usb port available not too far of a VGA ports.

Regarding operation, no problem, the distribution is ensured ... out of condition back in the head as the signal is duplicated and therefore transits a single image with a single resolution.
Do not confuse so, with small boxes that plug into a USB port and containing a graphics chip allowing you to choose a second resolution, which allows a second display by not duplicating but in addition, and extend your desktop or add a different window to use certain software more ergonomically.

This box is well what is expected, it is advisable to use the second port with a similar screen or video projector that will accept the resolution set by the PC graphics chip for the main screen.