Product Name: Sapphire Step Window with Thin Step Coating: HC Customized: Customized Certification: RoHS Lenses Color: Clear Material: Optical Glass Shape: Single-lens Transmittance: 90%-95% Type: Concave Lens Usage: Medical, Optical Color: Transparent Polished: Yes Diameter Tolerance: +0.0/-0.15 mm Thickness Tolerance: +/-0.1mm Surface Quality: 60/40,40/20 or Better Centring Error: <3 Arc Minute Bevel: 0.25mm