Product review (5 stars): GREAT!!!
My washer was shaking like crazy, adjusted perfectly and it still shook, my floor just wasn't solid enough to prevent the shaking. Put down a sheet of plywood and it was better but still not great. These things have made all the difference in the world. They have stopped all the walking and it barely shakes even on high spin.
A little tedious to place them under the machines but worth the effort and the cost. Make sure you have the surface super clean so they will stick well.