Auto Focus Sensor Z- For Lens Tube: D25mm for Automatic Motorized Up Down Table CO2 Laser Engraving Cutting machine The focusing sensor set must be working with automatic up and down table laserin-strument. Noticed: This item is not include laser head, mirrors and lens. Please make sure your machine supports Z before purchasing Note: Installation guide not included, we strongly recommend you professional installation. Please check as much as possible to make sure item is what you need. Tips: The product may be updated constantly ,Due To Different Batches, The Actual Product May Have Slight Differences Or Color Differences, Which Does Not Affect Use Color: As Shown Material: plastic Package Contents: 1 x Auto Focus Sensor Z- Only above package content, other products are not included. Note: Light reflection and different displays may cause color of item in picture a little different from real thing. The measurement allowed error is 1-3cm.