SPD including: power supply and signal lightning arrester and antenna-feeder SPD. SPD also named: arrestors, surge protector, surge protectors, short for SPD. In information times of today, computer network and communications equipment increasingly precision, its work environment of requirements also increasingly high, and lightning and large electrical equipment of moments had voltage will increasingly frequently of through power, and antenna, and radio signal transceiver equipment, line invaded indoor electrical equipment and network equipment, caused equipment or components damaged, personnel casualties, transmission or store of data by interference or lost, even makes electronic equipment produced errors action or temporarily paralysis, and system pause, data interrupted, Local and wide area network is compromised. Its shocking, indirect losses far greater than the direct economic loss. SPD is through modern electrical and other techniques to prevent lightning strikes in the devices.