I had heard that Polsilver were basically the same as the now discontinued Super Iridium. Fortunately I stocked up SIs when they were disappearing, even so, I noticed that Lee's Razors sells Polsilvers so when I was ordering from him, I added a pack of 10. Other than the name, the two blades seem to behave essentially the same. They both have the same kind of W logo on the packs so probably come out the same factory. If you missed out on Super Iridiums don't fret, Polsilvers will give you that same great smooth shave and they are available for about the same price as Feathers.