Amer Mount''s HYDRA1B Single Monitors Aluminum Slim Mechanical Spring Monitor Arm comes with Top Fix fitting, which means this type of arm is perfect for limited space underside of the desktop. Its optimizing elbow spring gauge offers the performance and quality needed for weight adjustment. Quick-release VESA plate and detachable joints make it an ideal support for longer life and easy installation. FEATURES Installs from Top Side: installs entirely from above the desk surface Smooth Arm Insertion: ensures easy installation Built-in Spring Tension Gauge: for perfect weight adjustments Spring-Assisted Mechanism: allows the workstation to easily move up and down Quick-Release VESA Plate: for easy installation Two Mounting Options: both desk clamp and grommet are included