So their fitlers 100% fit the Canon filter adapter? That wasn't entirely obvious from the site that I could see. Not that I am thinking of lending them money soon, just interesting to know.
I had the same question before trying to purchase last fall. They confirmed, their filters would 100% fit Canon EF/RF adapters and would be weather sealed.
I have several Breakthrough filters, they are very well made and have good optics (little color caste, etc), but they held my money for 4-5 months without delivering a product. That was long enough. Unfortunate to see it is still going on. I am not sure what the issue is, but...something ain't right.