H-K9L (N-BK7) optical glass is an excellent optical material with wide spectral transmission. It has excellent transmittance in the visible near-infrared range (350-2000nm), high hardness, and low content of bubbles and impurities. Therefore, it is often used as a substrate for various optical components Generally, H-K9L material is chosen when the additional advantages of JGS1 (good transmittance and low thermal expansion coefficient in the ultraviolet band) are not needed. We offer both uncoated and coated high-precision window panels, and customers can also customize the size and coating.