Material: Anisotropic synthetic sapphire crystal (Al2O3)Orientation: RandomDiameter Tolerance: +0.0, -0.10mmThickness Tolerance: +/-0.1mmClear Aaperture: >85% of diameterParallelism: <3 arc minutesSurface Quality: 80-50 scratch and digFlatness: 1 lambda per 25mm at 633nmBevel: 0.25mm time 45deg