Material: UV Grade Fused SilicaDiameter: 134mm ± 0.10mm Thickness: 3.00mm ± 0.10mmTWFD: < 2 waves @ 632.8nmSurface Quality: 20/10 (10/5 available upon request)Parallelism: < 30 arc-minutesChamfer: ProtectiveCoating: R< .25% @ 1064nm & < 10% @ 632.8nm @ 0º AOIClear Aperture: 85% minEdge Finish: GroundPlease see our E-Book on how to extend the life of your laser optics! http://info.unitedlens.com/debris-shields-manufacturing-and-procurement