墊片，高低速切換器

The 21mm inner diameter was spot-on for my mill's shaft, no slop at all. I love that it’s a solid metal piece rather than plastic, feels like it will hold up over time.

The 27mm outer diameter fits perfectly into my micro mill's shifter assembly, and the metal construction gives it a solid, precise feel. It slid right onto the shaft with no play at all, exactly what I needed.

I was worried the 5mm length might be too short, but it sits perfectly on the shaft and makes shifting much smoother. The metal feels solid and well-machined, no wobble at all.