Butt splices are crimp connectors used to safely connect one or more wires to another wire. Step-down butt splices are meant to connect a higher gauge wire to a lower gauge wire. They could also be used to connect two or more smaller gauge wires to a single wire. When selecting which type to get, pay special attention as to whether they are epoxy lined or not. Many manufacturers do not line the interior of their butt splices with a meltable glue. This epoxy reacts to heat and expands creating a superior environmentally sealed connection.