1. High-pressure dry reed tube: the glass tube is filled with inert gas, two ferromagnetic reeds and contact precious metal coating; compared with the ordinary dry reed tube, the gap between the reeds is larger, so as to obtain kV-level withstand voltage; the tube is completely sealed to isolate water vapor and oxidation. 2. Excitation coil: wound outside the reed switch, input DC control voltage (common 5V/12V/24V) to generate a magnetic field. 3. Housing/shielding structure: High voltage models will add insulation encapsulation, quarantine control side (low voltage coil) and high voltage load side.