Fail-safe galvanic isolators interrupt galvanic current with other boats in your marina when installed on a boat that is connected to shore power. It maintains the safety ground and solves the most common forms of corrosion and premature zinc loss within a boat's bonding system. In the event of a failure, it maintains safety by not compromising the ground continuity onboard when you are connected to shore power. UL certified and ABYC compliant. Meets ISO 8846 for ignition protection for mounting within an engine compartment. 120/240 volts. 7-1/4"L x 6-1/2"W x 3-3/4"H. UL certified & ABYC compliant | Promariner Fail-Safe Series Galvanic Isolator, (1) 30A or (2) 50A