Floureon 20A MC4 in-line Diode Connector Solar Panel Cable Connectors 20A in-line Diode Connector Solar Panel cable Connectors Practical and easy connector used between Solar panel and switch box to prevent the reversal of current. Contacts for the connector are copper, coated with tin for easy solder adhesion. Each end nuts comes with rubber bushings for air tightening. Diode built in the connector TUV-approved Connector head