Product review (5 stars): Easy to install with a helper
If you have a Whirlpool Cabrio with a creaking or knocking sound as it agitates, this may fix the problem.  Its the core of the suspension for the tube, and as such after relatively short periods of time (3 years in my case) it starts getting noisy.

Installing it is not difficult; there are videos on YouTube, which are worth viewing.

Despite what it shows, it is far easier to install this with a helper, as someone has to take the load off the suspension on each corner.  If you do it by yourself, you'll struggle a bit.

If I have a complaint, its that this part should never wear out.  And you can't tell from looking at it that its worn.  It seems like a design flaw.  But at least if you fix it yourself, you're only out $25.