JUKI Anti-Vibration cones OR plastic cone inserts for overlock sewing machine (JUKI MO-600 series) - thread spool stabilizer that keeps cones steady, reduces noise and shaking, and helps your machine feed thread smoothly at high speed.
With smoother thread flow, the stitches stay even and balanced, especially important in overlock stitching where multiple threads feed simultaneously.
Also, Protects the spool pin and cone base; The soft material (usually rubber or silicone) prevents wear on the metal pin and reduces noise or friction from the cone spinning directly on metal.