RS-232 Surge Protector, DB25, 4-Wire Serial, DB25, 4-Wire Serial
Here's why you need a surge protector: In an ideal world, the flow of electrical current in your computer systems would be equal at all times. No outside power disturbances would disrupt the balance of power in your electronic devices. In the real world, however, several forms of power disturbances can wreak havoc on your electrical devices. These power disturbances come in the forms of induced transients (which include lightning, electrostatic discharge [ESD], and noise), ground-loop currents, and surges.
Although only a lightning arrestor can protect against direct lightning hits, a surge protector can guard your equipment against damage caused by induced lightning. To understand the need for this protection, consider the enormous magnitude of energy that a lightning strike generates. As this large current flows through conductors, the expanding magnetic field causes induced current to flow in nearby conductors that could then carry damaging impulses to computers.