Here is a video review of the NiSi filter holder kit for Ricoh GR III (and the Q20ii flash):
Another NiSi filter holder kit for Ricoh GR III review:
One more review that includes the NiSi filter holder kit for Ricoh GR III:
DC.Watch published a review of the NiSi filter holder kit for Ricoh GR III:
Additional information on the NiSi filter holder kit for Ricoh GR III:
