The 521-9211F is a snap-in mounting clip designed for 3mm LEDs, providing secure panel-mount installation. The clip features a simple three-step mounting process: snap the clip into the front of the panel, insert the LED lamp from the rear, and secure with a retaining ring. Key dimensional specifications include a recommended mounting hole of 4.19 mm (0.165 inches), a maximum panel thickness of 2.54 mm (0.100 inches), and overall clip dimensions of 5.99 mm × 3.53 mm (0.236 × 0.141 inches). This mounting solution is compatible with a wide range of Dialight 3mm LED models and is ideal for applications requiring reliable, tool-free LED installation in control panels, instrumentation, and electronic equipment.