Derby blades are not sharp enough for tough beards, even with awesome prep, and too rough for sensitive skin. I have tried them several times (on my third tuck), most recently today. It was the worst shave in all the months of wet shaving (new blade). It could be it was a dud. But I wonder why I have not gotten such bad results with other blades, like the Astras. Anyway, YMMV, but for me Derbys are fail blades.