This article explains how to mount Elo widescreen monitors in portrait mode using a stand

It is possible to mount the larger sized wide-screen monitors (19" - 27") in portrait mode on the stand, however, they will have limited adjustments. They will not be able to stand straight up and down and the bottom edge of the monitor will rest upon the desktop surface.

See example below of the ET2202L monitor mounted in portrait mode on the stand: