You must use the provided desk clamp to mount the Flex Arm to your desk. Note that the lower part of the desk clamp can be temporarily removed in order to mount the desk clamp to a mounting platform with limited clearance (e.g. in a cubicle). If there is no space at the rear side of the desk, it may also be possible to mount the desk clamp through a sufficiently large hole in the desk plate (min. 100x10mm (4x0.4in.)).
WARNING: Because mounting surface materials can vary widely, it is imperative that you make sure the mounting surface is strong enough to support the mounted Flex Arm and Cintiq Pro. (For wood-based surfaces, a thickness of 25mm (1in.) or more is recommended.)