Product review (5 stars): works well, better on dryer
Easy to install.  Pull out appliance.  Place two "sliding pads"  under rear feet and slide applicance back into position.  Then, place front feet.

These pads did a better job of quieting the dryer than the washer when listening to the appliances on the same floor.  That is likely due to the amount of air-borne energy produced by the devices as the washer is loud due to the churning of the water and the sound of the motor.

Some reviewers are expecting miracles for $40.  The pads do what they can for the price of a rubber-like hockey puck that is 1" thick.  Additional floor dampening is possible with the installation of a rubber floor mat.  Additional air-borne sound dampening can be had with the installation of a heavier door and/or some adhesive sound mats such as DynaMat.