The Cokin Filter holder BP-400 is the beginning of the Cokin filter system. You can attach the filter holder to your lens by means of an adapter ring (52mm to 82mm). The holder has room for 3 filters which you can apply simultaneously. There is also room for 1 CP filter (maximum). To attach the filter holder to your lens you need an adapter ring. The Cokin filters have a size of 111mm x 85mm.