I wasn't too sure what to make of these brushes, but I bought them anyway. They have become my go-to cajón brushes, even though I own quite a few others.
The shaker baskets are super clever and useful, especially when you're playing at a lower volume. You can use them in many creative ways.
Lastly, the body of the brush is made of wood, so you can use THAT as an ad-hoc beater for blocks, güiros, etc.
Super recommended!