Material: Fused QuartzDiameter: 50mm ± 0.10mm Thickness: 2.00mm +0.15mm - 0mm TWFD: < 1/2 waves @ 632.8nmSurface Quality: 40/20Parallelism: < 45 arcminutesChamfer: ProtectiveCoating: R< .25% @ 1064nm & < 10% @ 632.8nm @ 0º AOIClear Aperture: 85% minEdge Finish: GroundPlease see our E-Book guide on how to improve the life of your laser optics!http://info.unitedlens.com/debris-shields-manufacturing-and-procurement