The APC Smart-UPS RT SRT3000XLi is a double-conversion online uninterruptible power supply rated at 3000VA/2700W, designed to give servers, networking gear and other critical equipment continuously regenerated, clean power rather than just battery backup on outage -- the "double conversion" design means load is always running off the inverter, so there's zero transfer time when mains fails. It includes a network management smart slot, serial monitoring interface, a cooling fan, and support for APC's optional external battery packs (SRT96BP) to extend runtime well beyond its internal battery. Physically convertible between tower and 2U rackmount form via the separate SRTRK4 rail kit, it's aimed at server rooms and data centre racks rather than home/office use.