IEC61643-21 is the recognized standards for top quality surge protectors, IT-FL422-SP have high respond speed, low output rudimental voltage, ascendance transfer performance. Interface using 4Pin crimping terminal, inhibition of lines on the high voltage pulse, protects the backend equipment to avoid damaged by lightning, industrial surge and electrostatic discharge overvoltage damage. This product uses metal shell, has good sealing property. It has the function of shielding and dust preventing corrosion. Products are connected in series, and installed in the front of the protected equipment.