APC Smart-UPS RT is a family of high performance UPSs for servers, networking equipment, telecommunication systems, industrial & medical equipment, & other mission-critical applications. Smart-UPS RT UPSs are based on the field-proven, industry-leading Smart-UPS functionality, but features 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.