I recently got my hands on this 5-pack of 4-inch nylon cup brushes, and I have some thoughts. First off, the quality feels solid—Swiss-made with coarse abrasive particles that tackle rust and paint like a champ. I used it on my old pickup bed, and it roughed up the paint without gouging the metal like a wire brush would. Huge win there.

But here’s the catch: speed kills these brushes. My angle grinder runs at 5000 RPM, and within seconds, the filaments started flying off like confetti. It’s frustrating because they work *so well* at lower speeds—I switched to a drill with the included adapter for moss removal on my driveway, and it was perfect. No sparks, no damage, just clean stripping.

The noise? Oh boy, it sounds like an angry beehive. But weirdly, that’s when it performs best—gripping bark and soft wood without harming the good stuff underneath. If you’ve got a variable-speed grinder or patience for drill use, these are gold. Otherwise, brace for a short-lived but intense relationship.