Finder Filter Fan 7F.20.8.120.4250.0 2 PACK - Thermal Devices - Thermal Devices
CONTAX Carl Zeiss Hologon 16mm F/8 T* Lens Finder Filter for G Mint from 2302059 | eBay
Raid Finder would use some more filters, considering how widely it is used nowadays : r/wow
10 search tips from a Mac Finder fanatic - CNET
Amazon.com : Solar Filter 2.50'' (ST250G) Glass Solar Filter Fits: View Finders, Cameras, Small Refractors, Spotting Scopes, and Binoculars; Celestron 9X50 Finder; Williams Optics 7 X 50 Finders : Electronics