This narrowband filter has a 7nm bandwidth of light centered on a wavelength of 656nm through, and reducing the transmission of certain wavelengths of light, specifically those produced by artificial light
OIII-CCD 7nm filter is designed for nebula observation allowing 7nm bandwidth of light centered on a wavelength of 500nm through, which corresponds to OIII emission lines, and reducing the transmission of certain wavelengths of light
Extra narrowband SIICCD 7nm filter (Sulful II for CCD) is designed for nebula observation allowing 7nm bandwidth of light centered on a wavelength of 672nm through, and reducing the transmission of certain wavelengths of light