Product review (5 stars): Works wonderfully. My washer would always vibrate a bit and ...
Works wonderfully.  My washer would always vibrate a bit and when I walked near it I could feel the vibrations in the floor.  Always annoyed me.  The Washer was perfectly balanced, but the spin and agitation cycle just had a lot of movement.

After adding these under it (which was a bit of a pain, simply due to having to slide the washer out and lift it up) I would say it was a 90% reduction in vibration.

I can stand right next to it now and not feel any vibration in the floor.