Battery terminal solder slugs were developed as a fast method for attaching a battery lug to a cable. Each solder slug is basically a pellet of solder with a flux core. To use a solder slug, you simply place the appropriate sized slug into your cable lug or battery terminal and heat it up using a propane or butane torch. When the solder melts in the terminal, insert the stripped end of your battery cable into the lug or terminal while keeping the heat applied for a few seconds longer to allow the heat and solder to transfer to the cable. When finished, you can protect your connection from corrosion using heavy duty heat shrink tubing. When used properly, solder slugs will eliminate the need for and expensive crimping tool, and create a more reliable and electrically conductive connection.