Sizes and coatings are available upon your request. You could send us your specifications or drawings. We will be happy to return a quotation ASAP as the average response time is within 24 hours. Meanwhile our optical designers are always available to assist with your special needs, and our factories in China are ready to meet your quantity requirements. Specifications: 1) Material: BK7 grade A optic glass 2) Diameter tolerance: ±0.0, -0.1mm (depends on dimensions) 3) Thickness tolerance: ±0.2mm or as requested 4) Clear aperture: >80% 5) Surface quality: 20 - 10 scratch and dig 6) Wavefront distortion: λ/10 per 25mm or as requested 7) Bevel: