Model Size: MGN 9H 420mm (16.535 IN) List: One MGN 9H 420mm, eleven M3 T-nuts, eleven 304M3H8 screws. Description: This product is an industrial standard component, the MGN9H 420 linear guide, suitable for applications in 3D printers, CNC machines, industrial robots, DIY equipment, and similar scenarios. Material Grade: GCr15, Accuracy Grade: Premium P, Travel Accuracy: ±0.01, Surface Finish: Nickel-plated (cross-section not plated). Friendly Reminder: After completing the installation of the linear guide, you can remove the silicone plugs at both ends. This is to prevent the slider from disengaging from the track.