These wire wheels are very cheaply made - I guess that's why they cost $.28/piece.They work fairly well on a 2-speed Dremel rotary tool on LOW speed, but when you go to HIGH speed they fall apart. Literally.I was using these brushes to clean out old lock tite and gasket seal from the threads on M6 and M8 engine casing bolts before reinstalling the bolts. I switched to HIGH speed and I was suddenly being pelted by metal fibers! I had metal fibers stuck all over my shirt, and the wire brush ended up looking like a porcupine that was having a very bad day.Not recommended unless you're only going to use these brushes on LOW speed.