Neutral density filters are optical components that uniformly attenuate various wavelengths of visible light without altering the color (spectral characteristics) of the light. Their core feature is: by absorbing or scattering light energy, the intensity of the incident light is reduced in a specific ratio (such as 10%, 50%, 90%, etc.), while the spectral distribution of the transmitted light remains consistent with that of the incident light. We offer two types of filters: one is made of neutral gray glass, and the other is achieved through metal film layers. They are widely used in photography and film shooting, optical measurement and instruments, display and projection technology, biomedicine and microscopic imaging, etc.