Allows screw-on filters with 77mm rear threads or Freewell 77mm Magnetic Filters to be used on lenses with 72mm front filter threads. The Freewell 72-77mm Magnetic Step-Up Adapter Ring permits the use of screw-on filters with 77mm rear threads be used on lenses with 72mm front filter threads. Alternatively this step-up adapter ring allows Freewell 77mm Magnetic Filters to be used on lenses with 72mm front filter threads. It features an aluminum alloy construction for durability while remaining lightweight.