Feather have an excellent range of razor blades, widely considered the sharpest blades available. Feather produce an outstanding range of Hi-Stainless Steel DE blades (61-S, 71-S & 81-S) These blades are all the same blade sold in different packaging & quantities. Feather also produce a Carbon Steel DE Blade (FA-10).
On top of these Feather is probably best known for their Artist Club style blades. A full breakdown/comparison of these can be found here.