Note:Dimension Tolerance: ±0.2mm 90°deviation tolerance Standard series: < 30 arc seconds Precision series: <10 arc seconds Super precision series: <3 arc seconds Surface Quality: Flatness: Standard series: l/2 at 632.8 nm Precision series: l/4 at 632.8 nm Reflectivity: R > 95% per face from 630 to 680 nm