this invention secures the breakdown voltage between stem pins or the like for high voltage service in a cathode ray tube . this insulator formed is of a clay - like silicone compound having a tip - throughhole and pin - throughholes or a stem base with the electric insulator mounted to the stem base : a inter - stem electric insulation device is structured by mounting either one of the electric insulator or the stem base with the electric insulator to the stem of a cathode ray tube and by pressing to fix together . this structure does not occur bubble generation caused by the electric insulator , and makes the handling easy , and furthermore , accomplish an automatic mounting of the electric insulator to a stem .