Received these as a freebie and realized how they got the name Derby - They don't last furlong (for long)!!!
I'm a Derby fan, actually prefer them over astra sp and personna blues.
Derby blades, Gillette 7 o'clock yellows and to an extent red Israeli personna blades are my 3 favorites.
I enjoy Derby blades in my R-41 and Fatip. The more aggressive the razor the more the Derby blades shine.