Ceramic heat-resistant ring of wear silk is used, therefore the product of 0.5 to 1.5 times higher than conventional power. Fever body to allow imports of wire into a spring-like penetration of the circle, ceramic, stainless steel jacket used in Japan, the Middle cotton high temperature thermal insulation (aluminum fiberboard) temperature to prevent leakage. Ceramic is a high frequency ceramics, heat transfer is fast and hard non-friable, high temperature deformation characteristics of aging is not easy