Ceramic gas discharge tube, abbreviated as GDT, is the most widely used switching device in lightning protection equipment. It has a high surge current of up to 1KA-150KA, extremely high insulation resistance, no leakage current, no aging failure, no polarity bidirectional protection, minimal static capacitance, and large dispersion of breakdown voltage. It is commonly used for lightning protection in communication lines, security units of communication distribution frames, and high-frequency circuits.