RENOGY Pair MC4 Male/ Female Solar Panel Cable Connectors Double Seal Rings for Better Waterproof Effect Renogy MC4 Cable Connectors are made with highest quality materials These connectors are also waterproof and resist dust build up These connectors are designed to complete a solar panel (PV) array, typically in parallel applications This connector is specifically designed for connecting photovoltaic solar systems with high mechanical requirements and extreme weather conditions Hard plastic One FFM and one MMF