A monitor stand assembly should be thought of in three parts:

1. Mounting Plate Assembly - there are currently FOUR standard monitor play assembly options.  One with no up and down tilt, and three others that offer up and down tilt with increasing strength and flexibility.
   
   

2. Post Assembly - Posts are either "telescoping" or "non-telescoping".
   
   

3. Base Assembly - The bases that work with post assemblies include  desk mount ( tubular, block, other substrate), desk edge mount, or wall mount.  They may accomodate a straight connection with the post or they may have elbows and offsets in them