They don’t drain anything. On the other side of the brass cup there’s rubber.
Product to sit between turntable feet and wood rack
I have set up a new (to me) Kuzma Stabi Ref 2 turntable. It has a steel (type) ball at the bottom of the Plinth’s footers, which I would never want to place directly on my Lignolab rack. I now use a Herbie’s Audio Lab giant cone/spike decoupling glider, with a thin piece of cork to help couple the ball to the brass disc inside of the Herbies decoupling glider. I am enjoying what I’m hearing, but feel as if a little experimentation is in order.