Check out these 5 stars reviews on STC Astro Duo-Narrowband Filter from the worldwide Cyclops Optics customers - Vendor and Group Announcements - Cloudy Nights
STC Filter - William Optics
Do users of the STC duo narrow band filter recommend it. - DSLR, Mirrorless & General-Purpose Digital Camera DSO Imaging - Cloudy Nights
AstroPixelProcessor on Twitter: "Astro Pixel Processor 1.068 has been released ;-) - Special Debayer Algoritmes for Dual Narrowband Filters like the STC Astro Duo & OPT TRIAD Tri-Band Narrowband filters https://t.co/PwXUpkOiuY #Astrophotography #
Rosette Nebula w/STC Duo Narrowband Bortle 9 ( Jeff Dorman ) - AstroBin