I recommend Feather blades. There are none sharper.
I understand they are a good product, but they are not American made. I also understand they are very sharp and unforgiving (what I assume is very aggressive). My beard is thick and I was considering using Feather blades as a back up if the ones that came with the safety razor did not work well. They did work well, I’ll stick with American made.
I'll second that. Good steel. I think I bought about 30 when I purchased mine. Will probably go for 100 or so next time I have to buy, so I'll be good for a few years. a box of blades takes up almost no space at all.