The Canon Drop-In Filter Mount Adapter EF - RF with Variable ND Filter is a mount adapter for EF and EF-s lenses for the EOS-R, with the option to use drop-in ND filters. As opposed to filters placed in front of the lens, these filters are placed between the lens and the body.

This means no filters are applied to the lens itself. In other words, all your filters will always fit. You can also change them out faster and you no longer need a specific ND filter for each mount format of your lenses. This makes it especially useful for lenses with a larger filter size and for lenses with a spherical lens element, like fisheye lenses and some wide angle lenses.

It also prevents vignette with wide lenses. Autofocus and image stabilization for the used lens remain intact. The adapter comes with a Variable Neutral Density filter (V-ND). The adapter is 73.2 mm in diameter and 24.7 mm high. It weighs 121 grams.