https://www.robbinsinstruments.com/collections/graft-prep-personna-double-edge-prep-blades
I get the Personna Med Prep blades by the box of 100 from this outfit. I tried 6-10 different brands of blades when I started using a safety razor three years ago. These turned out to be the best for my skin and razor.
I wonder what the differences are? I recall buying Russian Gillette knockoffs, but edges were rough. Some other brands had different edge bevel (is bevel, the angle, the right word?). I see Feather mentioned - they’re only for the stout hearted! I like a quick shave without blood. Old man Gillette really did a good design for a one-size-fits-all safety razor. I used to love their Platinum Plus.
I have a friend who works at Gillette who got me quality-control samples of their Russian DE. He complains how DE still has the world market, and they can’t get folks to buy their 13-blade, $6-per-shave crap.