The Patton Model 503 S-6 universal surge protector guards any RS-232 system (synchronous or asynchronous) against data loss and hardware damage due to data line transients. There are many data line surge generators: lightning strikes, fluorescent lights, elevator motors, even UPSs. AC protection alone is not enough! The Model 503S diverts harmful data line surges to chassis ground (through either D-shell) before they reach your hardware.