4. Mini Display Port, connect Mac Book, Mac Book Pro, or Mac Book Air.
This product with three output ports, and you can choose one of them to use at a time as you requested, the functions of the port as followings:
1. DVI output, connect the DVI devices using a DVI cable.
2. HDMI output, connect the HDMI devices using a HDMI cable.
3. VGA output, connect the VGA devices using a VGA cable.