90% transmission of the filters can block the light pollution of the city. Filter threads directly into the 2 inch barrel of your telescope eyepiece. 90% transmission means the filter also blocks the light from mercury and sodium vapour lamps. Standard M48x0.75 thread interface. The thickness of the filter can affect wavelength and dispersion of the filter. The filter can use with filter drawer and electronic camera. The Narrowband filter is designed for nebula observation. Package Includes:1x SVBNOY 2" OIII 5nm; 1x SVBNOY 2" H-Alpha 5nm; 1x SVBNOY 2" SII 5nm; 3x PP Material Plastic Box. SV226 filter drawer adopts integrated CNC molding and anti-light leaking design. It can also use 1.25" & 2" specifications on the market. Easier to install and pull out, but also provides effective installation protection, no need to worry about damage to the filter. Advanced CNC integrated molding processing, quality assurance. Thickness affects back focal length, which affects image quality and available accessory options. SV226 filter drawer can use with SV550 SV503 OTA or SV405CC SV605CC camera. The packaging is equipped with a plastic storage box to ensure that accessories around the filter drawer can be stored. The filter drawer comes with the M42-M48 adapter to resolve the thread compatibility issue. The interface can compatible with astronomical cameras of different specifications. Package Includes: Drawer Frame x 1PCS 2" Filter Slider x2PCS 2"-1.25" Filter Adapter x1PCS M42F-M48M Adapter x 1PCS Plastic Case x 1PCS.