Adapter ring for the Cokin P (M) Series Filter system.
The Cokin Creative Filter System consists of three main components: A filter holder / Adapter ring and a Filter.
Screw the adapter ring onto your lens.
Slide the filter holder on the adapter ring until it snaps in place. The filter holder is now solidly attached to the lens, yet it can rotate both left and right.
Slide the filter into one of the filter holder slots. The one closest to the filter holder housing is the narrowest; it allows the use of round filters with notched edges (polarizer, star filters..). The two central slots are intended for square filters. The outer slot can be used either for an additional filter or for a coupling ring.