Vesta Pro series - Intelligent line-interactive type: UPS with AVR Boost & Buck function. Power Factor is around 0.6. (This means that acual power is 60% of rating) VA range: 400VA ,600VA, 800VA & 1000VA, 1400VA, 2000VA. Common Application: CCTV, low-end DVR, low-end digital equipment, Office workstation, small server, small phone system, POS device etc. VP serial also can adjust incoming voltage very well. VP400/VP600/VP800 Disigned for office Workstation and PC Overload protection w/AVR Phone,Fax,& Modem protection VP1000/VP1400/VP2000 Designed for Office Workstation and PC Overload protection w/AVR Mutilple loads such as Large servers, phone systems, DVR's, etc. Acutal run time depends on load connected to UPS and state of batteries. How to choose the right size: Total all the wattage from all equipment you want to connect and multiply by 2. Use that number to match to the next highest model. Your run time should be about 1 hour or just less. Please note that UPS power back up systems are made to run your equipment through power surges, brown outs, and temporary power outages. Once your power is out for more than 10 minutes, you should shut down computers and other equipment. UPS systems are not made to power devices for long periods of time, rather, they are meant to stop inturruptions in equipment usage. Long term power should be supplied by back up generators if needed.