Product review (2 stars): Didn't work so well...
When I first received these, the bottoms of the feet were very sticky and seemed to be very durable.  However, as time went on, the washer started to dance its way across my floor.  Upon investigation, I found that the bottoms of the feet rubbed away which allowed them to slide.

Had the feet bottoms stayed intact, my rating may have been higher as the feet did seem to lessen the amount of shaking produced by the washer.