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