Product review (5 stars): They work.
I recently moved and only had three of the four locking things to secure my Samsung front-load washer tub. After unpacking and getting things set up we discovered that the washer has developed a serious power-walking habit. We're talking 6" or more per load. I spent hours balancing and leveling it, to no avail. Getting these things in without help was worrisome but ended up being a breeze using a large crowbar and a plastic block to protect the washer. Once they were in, the machine has literally not moved. 40 bucks seemed like a crazy price for little rubber feet but these worked and saved me a ton of money on repairs or replacement.