This is a arm mount for 13-35in monitors up to 26lbs (the vast majority of modern monitors will be well under this).
It's gas powered, so you can really easily adjust it in any direction and have it balance perfectly. It can clamp to most desks or tables, and it uses the VESA mounting standard so most monitors will be supported.
It even has a USB port in the base. It's a good monitor arm, and normally costs $90-100.
If you need it, I have two of them, and I'd sell both for $35.