. Lightning and power surges can permanently ruin your electronic equipment. Changes in voltage cause lockups and loss of work. This unit will protect your equipment from the threat of bad power. The Essential SurgeArrest series offers a great value for home equipment and business applications such as small office/home computersKey Product Info . IEEE let-through ratings and regulatory agency complianceLightning and surge protectionNoise filteringBuilding wiring fault indicatorFail safe modeCatastrophic event protectionData-line protection Product Features IEEE let-through ratings and regulatory agency complianceAPC surge protectors undergo stringent testing by IEEE and are awarded let-through ratings which indicate the maximum voltage level that can possibly reach your equipment after a surge or voltage spike has passed through an electric surge protector. Lower IEEE let-through ratings indicate better protection and performance. The APC Essential SurgeArrest series offers optimal performance with a let-through rating of less than 330V for North American products and a rating of less than 15% for products sold worldwide. Lightning and surge protectionTo prevent damage to your equipment from electric power surges and spikes. Noise filteringAttenuates EMI/RFI line noise that can cause data errors and keyboard lockups ensuring better performance of protected equipment. Building wiring fault indicatorThis LED informs users of potentially dangerous wiring problems in the wall circuit. Fail safe modeMost other surge suppressors continue to let power through even after their circuits have been damaged leaving your equipment exposed to future surges. APC's SurgeArrest fail safe which means that once the circuit of an APC SurgeArrest has been compromised the unit disconnects equipment from the power supply ensuring that no damaging surges reach your equipment. Catastrophic event protectionSurgeArrest components such as MOVs and Thermal fuse ensure instantaneous reaction to lightning strikes and wiring faults. If the surge components are damaged due to power spike or over voltage excess power cannot reach your equipment. Unlike the APC SurgeArrest products most surge suppressors continue to let power through even after circuits have been damaged leaving your equipment exposed to other damaging surges. Data-line protectionProtection of data lines (Ethernet Coaxial and Phone lines) ensures complete protection of your equipment from surges. It is very important to protect your equipment from back door electric surges traveling through data lines as they can be as damaging to your equipment as surges traveling over power lines. What's in the box? . User Manual