Transmission= Optical density 2.00 (1%T) @ 500nm Density Tolerance: +/- 5% 200-1000 nm Size=25.0 mm dia. x 2.5 mm thick Ring mount: Black anodized aluminum, 21 mm clear aperture Coating type= Front surface exposed, inconel (Fe Cr Ni alloy) Substrate: UV grade fused silica, < 3 arcmin parallelism, 60-40 scratch-dig Wavelength Range: 220-1200 nm