The AR-20 II delivers a stable stream of AC power to protect equipment from problems caused by AC line voltage irregularities such as sags, brownouts, or over-voltages - all of which can cause sensitive electronic equipment to malfunction or sustain damage. Featuring a generous 20 amp capacity, the AR-20 II accepts any input voltage from 97V to 137V and transforms it to a constant 120V. Voltages beyond this range are also converted to usable levels, unless they are extremely far out of range, in which case the unit will automatically power down to prevent equipment damage.