Freewell 77mm M2 Series Empty Base Ring (works only with Freewell M1/M2 Magnetic Filters)

Freewell Magnetic Base Ring This 77mm M2 Magnetic Quick Swap Base Ring from Freewell is designed for their magnetic quick swapping system. Once attached to the filter thread of your lens, it lets you swap out any of their M1 or M2 compatible magnetic filters quickly and easily. This means you can replace individual filters or stack densities and styles of various effects to suit your needs. This ring is not compatible with conventional and nonmagnetic filters.