astrodon-narrowband-filters
https://astrodon.com/products/astrodon-narrowband-filters/Astrodon Narrowband filters currently are provided off-the-shelf for:
Sulphur SII 671.6 nm 5 and 3 nm
Hydrogen-alpha H-α 656.3 nm 5 and 3 nm
Nitrogen NII 658.4 nm 3 nm only
Red Continuum RedCon 645 nm 5 nm only
Oxygen OIII 500.7 nm 5 and 3 nm
Other emission lines, bandwidths and sizes upon request
====
The difference in data in narrowband imaging
https://www.swagastro.com/narrowband-information.html