Victron's MultiPlus is a compact, elegant series of inverter/chargers featuring 120V of pure sine wave output, 120 amps of adaptive battery charging, a high-speed AC transfer switch, hybrid PowerAssist technology, and multiple system integration features.
The main AC output has no-break functionality. In the event of a power interruption, the MultiPlus takes over the supply to the connected loads in less than 20 milliseconds - fast enough that computers and other electronic equipment won't be disrupted. The second AC output is live only when AC is available on the input - useful for loads that you want to prevent from draining your batteries (water heaters, air conditioners, etc).
One of this inverter's best features is PowerAssist, which helps prevent overloading a limited AC source. When peak power is required for limited periods (i.e. startup surges), the MultiPlus immediately enlists assistance from the battery when the primary power source is insufficient.