Model Number: magnifying glass lens-G5H Brand Name: jiaxing Key Specifications/Special Features: Various styles are availableOptical glass spherical magnifying lensMaterials: soft PVC, N-BK7, sapphire, fused silica or optionalDiameter: range: 2 to 550mmSurface quality: 80-50, 60-40, 40-20, 20-10, 10-5Surface flatness: 1/20 to 1 lambdaConcentration: better than 3 minutesChamfer: 0.1 to 0.3mm x 45°Size tolerance: ±0.03 to ±0.1mmCoating: optional such as anti-reflective coating