Recently moved to a loft, and the stairs were really squeaky going up and down. Anyway, these items made all the difference, as they have cushioned the wooden stairs.

Although some squeaks can be heard, they have subsided by at least 95.  The items are well made and designed, with a rubber-like material below each tread.

Also, make sure that you get carpet tape, and run the tape vertically on both of the short sides underneath. It is really a preference thing, but save yourself some time.