Thanks to the Artesky filter holder you can internally connect a 2" filter screwing it to the present thread; then using the original RASA 8" ring nut, screw everything to your astrograph and take magnificent photos! Compatible with ASI ZWO ASI294MC-PRO, ASI1600MM-PRO, ASI1600MC-PRO, ASI183MC-PRO, ASI183MM-PRO, ASI2600MC-PRO and other with backfocus of 17.5mm