I got 500 of these sleeves when I was starting out with Dominion in April. I needed some more a couple weeks later, but they were in the middle of switching suppliers so they had no stock, and I had to get some "regular" Mayday sleeves instead. This is my observation on the OLD manufacturer vs. Mayday regular sleeves; the new manufacturer's sleeves might be different.
The Cataphract sleeves:
- were consistently sized. Out of 500 sleeves, only 2 or 3 were too narrow (grossly so, as if they were the "end of the run" or something), and there were a couple extras so it didn't really matter. My experience with Mayday sleeves has been a typical failure rate around 5-8% per pack, with a couple extraordinary packs pushing 60-70%.
- seemed slightly thicker/heavier-duty than the regular Mayday sleeves, but I have no measurements or evidence to confirm this.
- have a "stickier" feel to them (a little harder to shuffle), whereas the Mayday sleeves are much slicker and the piles sometimes slide all over the place.
Again, I can't vouch for the quality of the current Cataphract sleeves, but the ones I got in April have been great.