Dupes: 3006 and 4665 - should be merged. Only difference is space between "36 mm" or "36mm". It's unclear which is the standard -- Astronomik RGBs have no space but narrowband has spaces. Astronomik's product site uses no space. [url]https://app.astrobin.com/equipment/explorer/filter/3006/astronomik-h-alpha-ccd-6nm-36mm[/url] [url]https://app.astrobin.com/equipment/explorer/filter/4665/astronomik-h-alpha-ccd-6nm-36-mm[/url]