Specifications Material: BK7, Grade A fine annealed Dimension Tolerance: +/- 0.10mm Radius: +/- 1% Surface roughness RMS (nm) < 1.00 nm Optical face: super finished Coating: Al + protection layer (MgF2) transparent to UV Reflectivity: R > 50% @ 120 - 200nm, R > 70% @ 200 - 850nm Angle of incidence 45°