This RevoRing Swift Magnetic Variable Adapter Ring from H&Y Filters can be quickly and easily attached to lenses with 58-77mm filter threads, allowing select Swift System magnetic accessories to be attached in just seconds. It features unique self-retracting blade technology with threaded ends to secure on the front of a lens. Each threaded end has been designed to overlap, removing any possibility of light leak. This adapter is compatible with all magnetic B Modules like bridge rings, the drop-in filter rack and magnetic VND filters.