Product review (2 stars): Didn't meet expectations
My washing machine (front loaded Samsung, with stacked dryer on top) vibrates when the load isn't balanced and the spin cycle begins.  It's bad enough my wife thinks the house will fall apart, even though it doesn't bother me that much.  I was willing to try anything to appease my wife, even spending $40 on some "silent feet".  That seems like a really high price to pay for a few small pieces of fancy foam, but if it worked, I'd be happy.

Needless to say, these aren't miracle feet.  We still feel the washing machine vibrate the windows downstairs, or shake the beds.  My approach now is to try to do as much laundry as possible when my wife and kids are not home, because silent feet didn't save the day.

I'm not saying they don't work for others, but in my situation my wife still thinks the house will shake apart, and wants to try adjusting levels (done that), and everything else to stop our washing machine from shaking when it begins the spin cycle.  Don't have miracle expectations from these, or you will likely be disappointed.