When evaluating a desk-mounted monitor arm, the first step is measuring the actual desktop thickness at the intended mounting point. Manufacturer documentation must be matched to the specific part supplied in the box, as different variants within the same product family use distinct mounts.

Close-up of a rounded oak desk corner showing a visibly thick edge.
Rounded oak desk corners feature substantial edge thickness.

Standard Clamp Thickness Settings

For the Ergotron LX Desk Monitor Arm (product 45-241), the manufacturer specifies that the standard desk clamp attaches to a surface edge 0.4 to 2.4 inches (10 to 60 mm) thick. However, this overall interval does not mean any thickness fits without reference to the exact adjustment mechanism. The dimensional illustration for the standard two-piece LX desk clamp distinguishes discrete settings: a minimum threshold of 0.4 inches (10 mm) or less, a middle range of 0.47 to 1.38 inches (12 to 35 mm), and an upper range of 1.46 to 2.4 inches (37 to 60 mm). Consult the manual and diagram for the supplied clamp rather than assuming continuous adjustability across the entire span.

Alternative C-Clamp Edge Clearance

The standard clamp measurement must not be confused with alternative mounting methods. The manufacturer contrasts the standard two-piece clamp with an under-mount C-clamp, a low-profile top mount, and a grommet fixing method. The under-mount C-clamp requires 1.2 inches (31 mm) of unobstructed space from the desk edge for back-entry installation. Side entry is also permitted where desk geometry allows, without requiring this 31 mm rear clearance. This specification applies exclusively to the under-mount C-clamp and does not apply to the standard clamp.

Inspecting the Desk Edge

Beyond thickness, inspect the underside edge for any apron, rail, or wall gap. Map the arm's travel and nearby objects. For context on how other workspace equipment occupies desk space, a freestanding laptop stand footprint compares freestanding base footprint, while evaluating task lamp reach compares another moving object near the work surface.

Front view of a plain wooden desk with a long apron below the desktop and open knee space.
A long apron runs beneath the desktop, leaving the knee space open.
Close-up of a wood desktop edge with a horizontal support apron directly below it and a vertical leg nearby.
A horizontal support apron sits directly below the wood desktop edge near a vertical leg.
Home desk with an open dark-screen laptop on the surface, an angled task lamp at the right, a black chair, and a window in the background.
A home desk holds one open dark-screen laptop and one angled task lamp, with one black chair in front and a window to the side.
Back of a black monitor on articulated black arms with a threaded clamp rod passing down at the front edge of a wooden desk.
Articulated arms hold a monitor while a threaded clamp rod extends downward at the wooden desk edge.