I have never had good experience with Astra SP blades, but I was never quite sure why some people reported that the blades were sharp and smooth and others had negative experiences similar to my own. I can use the SP blades but get much better shaves with the Astra SS and other Gillette blades. Astra SP blades are inexpensive, but if quality control on the blades is poor, they do not represent a good value.