This is what ZWO writes on their website ( FAQ )
What Filters Are Built Into Seestar S50?
Seestar S50 is equipped with three built-in filters: UV/IR Cut filter, dark filter, and dual-band anti-light pollution filter (OIII 30nm/Hα 20nm). The switching of the dark filter is automatically controlled by Seestar. As for the UV/IR Cut filter and light pollution filter, users can switch between them in the app based on their own needs.
