The filter holder is literally the central element in the COKIN plug-in filter system. The adapter ring is turned into the screw thread of the lens in order to attach the Cokin filter holder to it. In other words, the filter holder plays the supporting role: the filter disc can be simply pushed into the filter holder from above. The advantage is obvious: Instead of buying your own expensive screw filter for all lenses in your photo backpack, a much cheaper adapter ring in the right size is sufficient. The various filters can thus be moved variably according to composition and requirements, which provides great creative scope for photographers and filmmakers.COKIN P series is aimed at users of mirrorless system cameras and medium DSLRs with standard lenses. The filter size is the medium version of the system.