This add is for (1) Cap, for PL-259 connectors. These caps have outside threads to screw into the PL-259 connectors on your unused coax lines. (They do not short the center conductor)This style cap will protect unconnected coax outside and will prevent stray RF from disconnected coax lines inside. They will also prevent arcing from a lightning hit which can be a potential fire hazard.This Protective cap is made from solid nickel plated brass. They will protect your outdoor connectors from moisture and bug infestation.There is no gasket on this cap but a little white grease on the threads will provide a good seal from moisture.I also offer a set of (5) caps in another listing!