Review on Mount-It! Dual Monitor Wall Mount Arms - Double Monitor Wall Mount with Full Motion Gas Spring Arms - Adjustable for 19-27 Inch Computer Screens (75 or 100 VESA Patterns) by Rory Stice

Mechanical build quality is excellent, doesn't feel cheap by any means. Easy to install, as long as you can work with a drill, screwdriver, spirit level and optional socket set, using a bolt finder is recommended. If you miss this or have trouble with any of the above, hire someone to do it. The only thing of real note is that the adjustable height is set by the weight of the screen against the gas spring and ultra-light monitors may not have enough mass to stay in the down position. and depending on the depth of the VESA mounting points on your monitor(s) you may need to purchase longer mounting screws separately as the ones supplied are quite short, only 20mm I believe. Otherwise a great product that is well worth the price.