TWO MONITORS AT ONCE: Fits most 17''- 30'' Monitors with the load from 4.4 -19.8 lbs (2-9KG) for each monitor, VESA compliant patterns 75x75mm or 100x100mm; While the whole VESA Plate of this product is 120*120mm,Pls pay special attention to the size of VESA Plate if your monitor are curved monitor, Or your VESA hole is inside a recession area. FULLY ADJUSTABLE RANGE: Your two screens will have 360° rotation, tilt angle +85° to -30°, swivel ±90° Upright up to 10"(260mm) and max extension is 21"(535mm). Both arms of the desk mount can be easily adjusted anyway you would like. ERGONOMICS: Improve your overall well being by creating most comfortable viewing angle for work or gaming- Enjoy the freedom to adjust your monitor height and angle: Your spine, neck and shoulder will be thankful DESK CLAMP OR GROMMET: You can choose one of two available ways of installation – C-Clamp or Grommet mount. The diameter of the hole in your desk must be 0.39-1.97 inch,Desk thickness must be within 3.54 inch, Kindly noted: (1) USB CABLES are NOT PROVIDED, The USB hole on the basis is ONLY for DIY purposes. (2) Monitor Cables and Cable Tie are NOT PROVIDED (3) Pls DON'T adjust the tension screw without the monitor mounted on it (4) Adjust method: If the monitor keep rising up, Pls reduce the tension screw (to the direction of "-") On the contrary, Turn to "+" .