Description: Four models(with different FL) anti-reflective coated focal lens for 40-100W. Focus lens is the fitting of CO2 machine, which is used to focus the beam after reflection, to realize engraving or cutting. Meniscus type lens, better foucs and meticulous path of light. Can withstand high power density, firm film, resistant to wipe. Used for processing, fits for engraving machine, marking machine, cutting machine, etc.. Specification: Material: Znse Lens Diameter: 18mm / 0.71inch Focal Length 38.1mm / 1.5inch 76.2mm / 3inch 101.6mm / 4inch 127mm / 5inch Coating: 10.6umAR Both Side Diameter tolerance: +0/-0.13mm Centre Thickness Tolerance: 0.25mm Focal Length Tolerance: = 90% Diameter Scratch/Dig: 40-20 Surface Accuracy: /2per1"Dia Package Includes:(3 Pack) 1 Piece Focus Len (Packed in boxes with foamed cotton)