Smart-UPS RT is a family of high performance UPSs for servers, networking equipment, telecommunication systems, industrial and medical equipment, and other mission-critical applications. Smart-UPS RT UPSs are based on the field-proven, industry-leading Smart-UPS functionality, but feature double conversion on-line topology, which delivers tight voltage and frequency regulation, zero transfer time to and from battery, and input power factor correction. While offering advanced performance and high availability features, the Smart-UPS RT can be managed using PowerChute software, as well as an array of SmartSlot 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 and battery packs ship in tower configuration, while easily converting to the 48,3 cm ( 19 inch ) rack-mount mode with the addition of an APC Rail Kit.