Neutral density filter (referred to as a density sheet) is a filter that attenuates the intensity of light without changing the energy distribution of the spectrum. Fixed neutral density filters that uniformly attenuate light intensity over a wide spectral region and are coated with durable metal coatings can be used in applications such as natural light and lasers. Fixed density filters are divided into absorption plus reflection density sheets and low reflection density sheets (ND4 mirrors), which are neutral attenuation of light over a large spectral range, and are also particularly suitable for calibration of optical systems. Products in stock are shipped immediately，Density sheets of special size, density and wavelength can be customized