The ZWO 8 position filter wheel attaches to the ZWO ASI1600MM-Pro monochrome camera. It holds filters for luminosity, red, green, blue, hydrogen-alpha (H-a), Oxygen-III (O-III) and sulfur-II (S-II). There is one additional slot for a “dark” or “shutter” filter which is used to create dark frames. Each filter is 1.25″ in size which works well with the 4/3 sensor. Click here for more information and where to purchase