... 20mm co2: Surface quality: 20-10 Focal length:50.8mm E.T:2.0mm Dameter:18mm Apply:Laser cutting ,engraving machines ... °Coating: AR/AR 10.6um The parameter for laser lens Part Nodiameterfocal lengthshapeD20-120mm38.1mmPX, PV, CV-CXD20-220mm50.8mmPX, PV ... ''PX, PV, CV-CXD20-820mm7.5''PX, PV, CV-CX Part Nodiameterfocal lengthshapeD25.4-125.4mm38.1mmPX, PV, CV-CXD25.4 ...