The Sensei PRO 55-52mm Aluminum Step-Down Ring permits the use of 52mm threaded filters on lenses with 55mm filter threads. It has large side knurls to provide a more textured grip when mounting or removing it from a lens. This step-down ring features a lightweight, aluminum-alloy construction that has a corrosion-resistant, matte black, hard anodized finish for durability and to minimize reflections.