Product review (5 stars): What a difference
I have a Kenmore front loading washing machine that I bought about 4 years ago.  Like all front loaders, it spins at very high speed to remove excess water from the clothing.  For the first three years, the washer sat directly on the tile floor.  We are also on an upper floor.  The washer sounded like a jet at takeoff during the spin cycle.  You could hear and feel it from every room in the apartment.  I'm sure our downstairs neighbor was no fan either.  With a baby on the way, I realized our laundry needs would increase dramatically and I started searching for a solution to the noise and vibration.

I bought these feet.  They were easy to install, with two feet designed for easy sliding, and two that are sticky (without adhesive).  The jet engine has been reduced to an almost pleasant white noise, and the vibration is gone completely.  It's spinning right now and just to be sure, I walked over and put my hand on the tile an inch from the washer.  Absolutely no vibration in the floor.  Remarkable.