Product review (5 stars): Vibbbbbrraaattions Stopped.
Have an LG front loading washer that could never reach full spin.  I had to turn on vibration Spinsense, tried leveling, etc.  Finally bought these, releveled just before installing these, and now the thing reaches full speed and I turned on the Spinsense.  Using these on the first floor, so I can't comment on the second floor benefits but they definitely made a big difference for me.