This on-line UPS provides clean, regenerated power directly from the battery 100% of the time. With AC>DC>AC conversion no surges or line noise can reach connected equipment. Special Pro features include a four year warranty on all electronics, a three year warranty on the batteries and a professional grade rack mounting kit. These models also feature a $50,000 connected equipment protection policy. Front panel LCD meter shows operating and battery status information. The NXRT-PRO Series models may connect to an unlimited number of external battery modules to provide theoretically limitless support power run time.