Product review (4 stars): Works, but won't fit all appliances...
I read all of the reviews of this product before purchasing, and despite what I considered a pretty high price decided to give these vibration feet a try to quiet  the vibration of a chest freezer.  The freezer is fairly quiet as most models go, but we recently relocated it to a spot in the mud room where it seems to vibrate through the floor system more noticeably that the previous location on a concrete floor.

The item description didn't give much information about the actual size or profile of the feet, and the photos of a black blob didn't do much either.  I had envisioned something much different.  The base is about 2 1/2" in diameter, angling up to about 2 1/4" at the top. in a slight cone-shape.  The height is about one inch, but the center is recessed at the top, slightly dished in by about 1/4".  So the actual foot of your machine cannot be larger than 1 3/4" in diameter.  Your machine will be raised about 3/4" higher that previously.

The bottom half of the product is a softer rubber material than the top half, and two of the feet have  a slightly sticky grip type bottom, while two have a slip-type fabric to allow you to place them at the rear and slide your machine back towards the wall before placing the gripping isolation feet at the front.  This is to keep a washer or dryer from "walking" across the floor.

In my case, the feet of my freezer are larger than the 1 " recessed top, so I had to make a wood shim to bridge the difference and keep it from crushing the outer raised lip.

Installing them with the "sliding rear feet" method went well and once in place the product seems to have nearly eliminated in the vibration through the floor.  The additional raised area now makes it possible to clean under the appliance and doesn't affect the ability to access or operate it.

Worth the money??  Maybe, but for the price I would have expected a flawless product with no tweaking needed.  If I had known the design, I may have experimented with other methods first.