Bold-K agency (filled square K)K
USA
K
Mark: Bold filled letter K
Recognized endorsed by 1 major authority
COR
Unknown
Bold-K mark shown bottom-right on back of COR Kosher Symbol Card; exact agency not confirmed.
How to use this safely: a listing here is not an endorsement. Only trust an authority if one you (or your community) already follow recognizes it — see the “endorsed by” tags above. Standards vary by community and by individual ruling, so always confirm with your rav.