The Drop-in Filter Mount Adapter EF-EOS R is a great way to expand your available lens options while also providing the ability to add a drop-in filter to your photographic endeavors. This adapter lets you utilize a circular polarizing filter, and because it's one size fits all, there's no need to purchase multiple filters to fit various lens diameters. The Drop-in Filter Mount Adapter EF-EOS R's matching design means smooth connections while a rugged, dust- and water-resistant construction adds to its flexibility, making it easy to have a high-quality filtering system without having to carryingAround multiple adapters and filters.