Good gracious, I thought everyone used electric razors, or am I missing something here and this is blades for electric razors. Sorry, I don't have to use one myself (lucky me) so I don't know much about them.
To be honest I cant see them having much effect, to sharpen a blade correctly it will need to be sharpened from both sides to remove the burs, it may extend the live by an extra shave but I doubt it will do much more.