I have recently bought DELL U3423WE monitor and tried to install Xiaomi Mi Computer Monitor Light Bar which simply did not fit.
This adaptor allows you to use your LED bar for 1800R monitors (tested on U3423WE).

The LED bar weight is too large to fit between the monitor and it's stand, so you have to use a double sided tape to attach it.

You only need extra 2x M3x8 screws and some tape.