Feather blades are made of stainless steel and are manufactured in Japan. I have found these blades to be extremely sharp. They have a platinum layer that helps the blade retain sharpness. Some people have complained that these blades are actually too sharp and can leave to irritation or cuts. I find the shave from these blades to be superior to any others I have tried. I use these blades for four to five shaves before replacing. Buying larger quantities, you can get these fairly cheap.
Another great blade is the Derby Extra. I find these blades to not be as sharp as the Feather. For some people this may be a good thing. The price on these blades is very very reasonable for the performance. With these blades I usually shave four to five days as well. For the price however, you could switch these blades out more frequently and the price would still be very reasonable. This may be necessary as I have experienced some of these blades just don't shave very well. At any rate, you can expect a pretty decent and close shave with these double-edge razor blades.