I make my own solar cables and often need these MC4 connectors. They fit great and ensure a solid connection. They're weather-resistant, snap tightly for a secure fit, and won't come loose. This is a complete set of 25 pairs of female and male connectors including metal core connectors for both. They crimp cleanly and provide a strong and durable connection. These are high quality MC4 connectors rated up to 30A DC and I highly recommend them. They get 5 stars from me.