Tripp-Lite and apc make excellent units. if used for a pc only, you might want to look at an ups (uninterruptable power supply) by apc. i am using the xs 1500 ups by apc. this unit conditions the line power, holds the voltage to one level as the line voltage varies, and surge protection built in. when my electricity goes off, my pc does not know it. absolutely no flicker. gives me 20-25 minutes to finish and shut down.