Traditionally, filters are attached by screwing them into the filter thread at the front on the lens. This applies both to round filters and to square filter systems, where the filter holder screws on to the lens via an adapter ring. Magnetic filter holders attempt to speed up the whole process using magnets rather than screw threads.
The advantage is that you can snap filters on and pull them off without fiddling with screw threads, and the magnets are perfectly strong enough to provide a secure attachment for the filter.
However, you will need an adaptor for the lens. This screws into the filter thread as usual and provides the magnetic base for the magnetic filters. Filter maker H&Y, known for its clever Revoring filters, has designed a magnetic square filter system called Revoring Swift.