Closed end connectors can be used as a splice, wire butt, parallel or dead-end cap. The outer shell of the connector is made from nylon. It is designed to insulate and protect the connection. The inside barrel is tinned copper and offers excellent conductivity. Use these connectors to create a fast, inexpensive, permanent electrical connection. To use, insert the wires into the closed end connector. It is important to ensure that the bare wires are within the internal barrel. Next, crimp using the proper tool. These connectors are ideal for connecting multiple wires together. They are for use with either solid core or stranded wire. Each size has a minimum and maximum range or wires it will accept. These are available in nylon insulation only.