NDT Fusion Auto Adapter - Canon EF Lens to L-Mount Cameras w/ Variable ND – Fotodiox, Inc. USA
Amazon.com : JJC 82mm ND Filter ND2-2000 VND Variable Neutral Density Fader for Canon EF 24-70mm f2.8L, EF 16-35mm f2.8L, Nikon AF-S 24-70mm f2.8E, Sony FE 24-70mm f2.8 Lens & Other Lenses
49mm Adjustable ND Filter ND2-400 Neutral Density for Canon EF 50mm 1.8 STM Lens | eBay
Canon Drop-In Filter Mount Adapter EF-EOS R 3443C002 B&H Photo