The Smart-UPS SURT1000XLI-NC capacity is 700W 1000VA & the RT UPSs are based on the field-proven, industry-leading Smart-UPS functionality, but feature double conversion on-line topology, which delivers tight voltage & frequency regulation, zero transfer time to & from battery, & input power factor correction. While offering advanced performance & high availability features, the Smart-UPS RT can be managed using Power Chute software, as well as an array of Smart Slot accessories. Smart-UPS RT provides battery back up to the load through the use of internal batteries. However, an unlimited number of external battery packs can be added to meet desired levels of runtime. All Smart-UPS RTs & battery packs ship in tower configuration, while easily converting to the 19" rack-mount mode with the addition of an APC Rail Kit.