X Arm, Extension and Collar KitConvert an existing LX Arm to hold two monitors, creating an LX Dual Stacking Arm configuration. This kit easily attaches to the pole of the desk mount base.Recommended for use with the LX Desk Mount LCD Arm, Tall Pole.BenefitsEasily add a second arm to your LX desk mount to hold another monitor or laptop computerCable management feature routes cables under the arm, out of the wayEasy to use: Simple installation and effortless operationPatented Constant Force™ lift-and-pivot motion technologyPasses Ergotron’s 10,000-cycle motion test, which ensures years of trouble-free height adjustment