This PolarPro Base Plate for Helix Magnetic Filters is a magnetic adapter ring that mounts directly onto the filter threads of a lens. Once mounted, it is compatible with all of the filters in the Helix magnetic filter system. Providing a secure attachment with a magnetic connection plus a quarter-turn locking mechanism, the Helix system makes installing and removing filters lightning fast. Each base plate includes a Defender Cap for ultimate lens protection when no filter is installed.