Fill the glass bowl with water and antibacterial soap or makeup cleaning solution, then slip your makeup brush into the rubber collar on the spinner. There’s a corresponding collar for nearly every sized brush.
Choose the level of agitation you’d like (depending on how dirty your brush is) and let it spin to clean for around 10 seconds. Then, lift the brush out of the solution and allow it to spin for a few more seconds, which helps it dry.
It’s a hygienic solution and quite the spectacle to witness, too.