Product review (5 stars): stopped the vibration!
I did lots of research selecting my first front load washing machine, but I guess I missed the part of how front loaders can vibrate out of control if its not on a sturdy concrete floor.  I spent hours adjusting the machine till it was perfectly level, but that did nothing to stop the violent vibrations during the spin cycle.  I was afraid my new washer was going to destroy the flooring (wood floor with tiles).  Luckily I came across this product online.  After placing these rubber pads under the washing machine, the vibration on the floor was reduced 90-95%.  The washing machine still vibrates a lot, but the rubber pads do a tremendous job absorbing the vibrations and preventing the energy from transferring to the floor.  Although the price is a bit high for 4 rubber pads, they work as advertised.