SPMZ7 series PTC thermistors degauss the shadow mask of color picture tubes by reducing the alternating current flowing through the degaussing coil within a short period of time. Owing to their degaussing function SPMZ7 PTC thermistors have been widely used in color CRT's degaussing circuit such as color TV sets and color monitors. Deriving from effects of earth magnetic system, effective omission of CRT's shadow mask improves color hindrance.