Breakthrough Photography Drop-in Filters for RF-EF Adapter - Newsshooter
Breakthrough 62mm X4 Neutral Density 6-Stop - Kamera Express
Breakthrough Filters UK - Neutral Density Filter Guide If you are unsure of when and where to use an ND filter or which density to use take a look our our latest
Breakthrough Photography announces more than 20 drop-in filters for Canon's EF-RF adapter: Digital Photography Review