Factory-installed option allows units to be used when running a generator or in marine applications when connected to shore power. Allows appliances to run on 110/230V AC current when available and automatically switch back to 12/24V DC power when AC current is not available. Option must be ordered at time of refrigerator/freezer purchase; call for details. Application: Allows appliances to run on 110/230V AC current when available and automatically switch back to 12/24V DC power when AC current is not available, Works With: SunDanzer Refrigerators/Freezers