Gas tube arresters (GTA) or gas discharge tubes (GDT) provide protection against voltage and current surges in electronic and electrical equipment. Surges can occur naturally or artificially. Natural surges may be the result of lightning or electrostatic discharge (ESD). Artificial surges result from induction loads and electric switches, and when devices are switched on and off. Gas tube arresters and gas discharge tubes are often used with telephones, optical transmission applications, alarm systems, modems, security systems, audio systems, and antennas.