Product review (1 stars): Made the vibration *much* worse...
- I have stacked front-loaders on the second floor that vibrate the whole kitchen under them when the washer is in the spin cycle, so based on the many glowing reviews I got a set of these.  After putting them in the vibration was even worse than before; not only downstairs in the kitchen, but the washer and dryer themselves visibly swayed from side to side rather alarmingly with the the "Silent Feet", where they pretty much simply vibrated in place without them.
- I removed them and now they're gathering dust.  I knew it was a gamble, and I lost.  (shrug)  Hope this helps set appropriate expectation....