Can take both or just one.
1 x dual monitor stand for 13-27" screens (held 28" OK but did slip down now and then). Can find the info for this one on amazon if you use the info from the picture.
1 x single monitor stand I think for larger screens as had no issue with the 28" but I can't find where I got that one from.
Both clamp onto your desk. My desk is about an inch thick and they had no issues attaching to that. Might be missing some of the screws for the vesa mounts but they should be easy to get. Both are in great condition, nothing wrong with them I just upgraded to a triple mount with a different layout.
Dual and single monitor stands (CH43 prenton)
This offer has been gifted to someone and is no longer available.