The connector on your display cable is a VGA video connector (3-row D-Sub 15 connector shown below). To connect your display to a computer or graphics card with a Macintosh-type connector (2-row DB-15 connector), or to a graphics card with both VGA and Macintosh connectors, you need to use the VGA-to-Mac adapter that came with your monitor.
1. Turn off the power to your computer and connect the Macintosh (2-row DB-15) end of the adapter to your video card and tighten the thumbscrews.
2. Connect the monitor cable to the VGA end of the adapter and tighten the thumbscrews as shown below.
3. Power on the computer.
The viewable image size of the Apple Studio Display 21 is 19.8 inches, the Apple Studio Display 17 has a viewable image size of 16.0 inches.
Important: When using the Apple Studio Display 21, the USB connector is needed for your computer to work correctly with your monitor. If the connector is not attached properly, the software controls are not available.