Designed for LX Desk Arms: Upgrade an LX Desk Arm, LX Dual Direct Arm or LX Dual Stacking Arm with an adjustable rotation stop to control the range of motion of the extension arm Simple installation: Includes dual rotation stop collar, two stop posts, set screws and adjustment tool; easily and securely attaches to the 35mm diameter pole Customized motion: Prevent monitor extension arms from coming into contact with walls, desk panels or dividers; establish a home position for your monitor arm for easy resetting after projects Streamlined and functional: Adjustable, anodized silver design fits the needs and aesthetics of any workspace Built to last: Extensive quality testing ensures your rotation stop holds up to everyday wear-and-tear; Ergotron products set the standard for quality with a 10-year warranty and expert technical support