The Drop-in Filter Mount Adapter EF-EOS R from Canon is a great way to expand your lens options and add a drop-in filter to your camera setup. This adapter lets you use a variable ND filter, and because it's one size fits all, you don't need to buy multiple filters to fit different lens diameters. The Drop-in Filter Mount Adapter EF-EOS R's matching design means smooth connections and a rugged, dust- and water-resistant construction that makes it easy to have a choice when it comes to your gear.