This is a 72mm adapter ring, for use with the Nikon AF-4 filter holder.
Nikon 67mm Adapter Ring for AF-3
Nikon 62mm Adapter Ring for AF-4
Nikon 52mm Adapter Ring for AF-4
Nikon 77mm Adapter Ring for AF-4
Urth 72mm Magnetic Adapter Ring
Cokin P472 72mm P Series Adapter Ring
