I am selling an ANTLIA astronomical imaging filter. This filter is suitable for shooting with a monochrome camera. ・Antlia 3nm Narrowband Oxygen III (OIII) Pro Filter - 36mm Since I have kept it set in the filter wheel since I purchased it, the filter is in beautiful condition with no scratches or clouding. This product is for astronomy enthusiasts, so I will omit detailed explanations. I am selling it because I plan to switch to a 2-inch size.