Provides protection of connected equipment from power surges on the data lines. Reduces line noise that can cause data loss and keyboard errors. APC 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. All APC products comply with local agency safety requirements, including UL in North America and CE/Kema/Gost/C-tick/A-Tick/Telepermit in their respective regions. Indicator illuminates when connected equipment draws more power than unit’s capacity. To remedy the condition, unplug less vital equipment. SurgeArrest will warn you if its circuitry has been damaged by heavy strike or power line surge and it is unable to provide 100% protection. If still under warranty, APC will then replace your damaged SurgeArrest free of charge.