Setting the proper focus in your K40 – American Photonics
ATOMSTACK Portable Laser Engraving Machine P7 30W, Mini Laser Engraver 5W Output Power for Metal Engraving, Wood Laser Cutting, Eye Protection Fixed- Focus, 200x200mm - Walmart.com
Amazon.com: ATOMSTACK P7 M40 Laser Engraver, 40W Portable Laser Engraving Machine, 5W Output Power Laser Cutter Support LightBurn, High Accuracy DIY Laser Engraver for Wood and Metal
Z Axis Height Adjuster, Z Axis Focus Control Set for TTS 25 TTS 55 -5.5S Engraver, Module Lifting - Walmart.com