The Patton EPG Model 501LC low capacitance surge protector lets you extend RS-232 cable runs to their maximum distance, while providing reliable transient protection. While standard data line surge protectors can reduce the maximum RS-232 cable distance by as much as 8%, the Model 501LC adds an insignificant 45 pF of capacitance per signal. It appears to the system as just a few inches of cable! This is accomplished using the same hybrid technology that's found in our high speed LAN surge protectors. The Model 501LC incorporates Silicon Avalanche Diodes for quick clamping, without wearing out. Transients are shunted to chassis ground bi-directionally via pin 1. If the Model 501LC encounters a severe surge above its rating, all signals will be balanced to ground if the unit fails. Your hardware will always be spared!