The heart of the COKIN Creative System is the filter-holder. Once attached to the lens, thanks to an adaptor ring, it can carry not only round and square filters but also modular accessories (modular hood, coupling rings etc...). The notches found both on the filter-holder and on the edge of round filters enable you to rotate the round filters to just the right position. Square filters slide within filter-holder slots in order to decentre special effects.System "A" for lenses between 36 and 62 mm in diameter is recommended for focal length over 35 mm.