The 2 piece BNC compression connector designed to make sure you get a video signal every time. The separate pin fits directly on the center conductor of your coax cable and the BNC sleeve compresses onto the jacket. The advantages are connection reliability, cable signal ingress/egress elimination, and waterproofing. Compression style connectors seal between the connector and cable. Aside from eliminating the opportunity for moisture to leak into the connection this seal keeps your signal inside the cable and keeps unwanted signals from entering your system through openings in the connection. They come in bags of 50, extra center conductor pins are available, Model number CT-BNC59-PIN, and require a compression tool Model number CT-CCT-BFR2.