Ceramic pulley (wire jump prevernter) y is to prevent the wire jumping out from it is route.The precision ceramics circle inside has an ultra-fine polishing degree Ra0.2.There is a hign-speed bearing in this porcelain circle which can control the sliding distance between enameled wire and the circle under 0.2mm.protect the film and assure the beating of the enameled wire in a very small scope to stabilized the tension.