This is a 67mm adapter ring, for use with the Nikon AF-3 filter holder.
Urth 86-67mm Adapter Ring for 100mm Square Filter Holder
Nikon 62mm Adapter Ring for AF-3
USED Nikon Mount Adapter FTZ
Urth 86-77mm Adapter Ring for 100mm Square Filter Holder
Cokin Z477 77mm Z-PRO Series Adapter Ring
Tiffen PRO100 Adapter Ring 62mm
