I read from another thread someone here has been using the Astra SP's since the early 1980's. That got me wondering, out of all the blades still made today, which one has been in production the longest?
You may need to refine your question a little. Do you mean as a distinct brand? Does significant changes to coatings, honing or anything matter?
Gillette Super Thin?
Does Gillette still make the Trac 2?
Not technically a DE, of course.
Gillette Super Thin?