The OPTI-UPS Enhanced Series ES550C USB 550VA/330W Line-Interactive UPS with AVR offer the highest power capacity and the best equipment protection around. Not only do they protect against blackouts, sags and surges, but with the added features of AVR (Automatic Voltage Regulator), the ES550C USB UPS ensure that only the cleanest power can reach your valuable equipments. Now with added feature to support USB communication with power management software.