The Parallax 7355 is a single stage converter/charger which is used in most newer Airstreams. It is not a very good unit in that it only charges at one voltage, not three as is best for batteries. As mentioned, it is not an inverter, it is a converter/charger 120 volts to 12 volts.
You can use it but it is far from optimum. Progressive Dynamics 9255 is a good one, and other 3 stage converters are available. Randy at bestconveter.com is a good phone source for information and products.