Waterdrop PF45 Replacement for Brita® Stream Pitcher Water Filter, Brita® OB05 Filter Pitchers and Dispensers, Pour Through Filters, Upgraded 7-stage Filters, Reduces Chlorine, 2 Months, 6 Pack

Just found this off-brand filter on Amazon. No affiliation, and i haven't tried it yet. But the reviews feel promising for the Slim (less so for the normal pitcher style). https://a.co/d/09niEqD4