The Magne-Fix Circular Polarizer, Small. 20mm Outside Diameter from Cokin gives photographers with unthreaded camera lenses a chance to achieve special effects and filtration that they might not ordinarily have a chance to do.
This system features a unique mounting technique whereby you peel off a protective film from the back of a mounting ring that contains an adhesive surface which is then pressed against the edges of your lens. The reverse side of the mounting ring is magnetic. The Magne-Fix Circular Polarizing Filter is then held firmly against the magnet. When finished with the filter, grasp it firmly and remove it.
Note: Cokin has performed tests to ensure that the magnetic system does not create interference with cameras or phone devices