You could ask the fellow from Eastwood directly.
If the patent has been granted, you can obtain a copy and see just what they have done. Like I said before, patents only protect Eastwood against commercial exploitation. You or anyone can use the patent filing to duplicate the device for your own use, can tell others how to make it, but cannot make it for others. Patent law exists this way to foster innovation while protecting the commercial nature of the use of patents. You may, after duplicating the device, find a better way to do the same thing or it could inspire you to create something entirely new.
From what the fellow said, the device creates a vortex that keeps the media from caking. It's probably $20 worth of hardware and $20,000 of development. Paying $129 seems reasonable for the time and effort required to duplicate it from the patent drawings.
To better answer you original question, a buddy purchased it and it works as advertised, which is to say "like magic". I plan on purchasing one so I don't have to drive so far to use his.
But if you do track down the patent, post a link to it here.