If you have a monitor with a 200mm x 200mm VESA hole pattern and want to mount it using a VESA adapter plate, you will need to find an adapter plate that is compatible with that hole pattern.
One option is to look for a universal VESA adapter plate that supports a range of hole patterns, including 200mm x 200mm. There are several such adapter plates available on the market from different manufacturers. Make sure to verify that the plate is compatible with your monitor's weight and size specifications before purchasing.
Alternatively, you can look for a VESA adapter plate specifically designed for monitors with a 200mm x 200mm hole pattern. These adapters are less common, but there are still several options available on the market. Again, make sure to verify compatibility with your monitor before purchasing.
When selecting a VESA adapter plate, pay attention to the weight capacity and size limitations of the plate to ensure that it is suitable for your monitor. You may also want to consider factors such as adjustability and ease of installation when making your selection.