This spare filter holder is designed for SVBONY SV226 filter drawers,It provides you with a more convenient combination. CNC integrated molding; more precise production process; strong and sturdy.With this filter drawer holder, you will be more convenient to use filters for deep sky photography; can accommodate 2-inch round, mounted filters, along with other 2-inch round filters that measure 50.8 mm wide and 7.5 mm thick. The SCBONY SV227 OII filter is designed for nebula observation and reducing the transmission of certain wavelengths of light. The larger the optical density, the clearer the image details. You can connect to your 2 inch eyepiece and make the sky you see even better. 90% transmission - whether under dark skies or under the sky glow of a city. The thickness of the substrate can affect parameters such as wavelength and dispersion of the filter. The Full Width at Half Maximum (FWHM) is about 5 nm. The OIII filter is designed for nebula observation allowing 5nm bandwidth of light centered on a wavelength of 500.7nm through. M48x0.75 thread interface adapts to most devices.