I purchased this after getting a new desk, where my older dual monitor mount with the clamp attachment would not work. I wanted one with both a grommet attachment as well as a base, in case I did not like the monitor placement from using the grommet. I ended up attaching this to my desk with the grommet.As other reviewers mentioned, it is not perfectly level between the two arms. When I have both monitors mounted and side-by-side, there is a 1-2cm difference between left and right monitor height. On initial setup it really annoyed me, but after a week, it doesn't bother me at all anymore. I did not try to adjust the rotation of the main support pole to find an ideal \lean\" to even out the arms as did another reviewer