Introducing the all-new Waterproof Solder Wire Connectors! These connectors have polyolefin tubing on their exterior and heat-melting adhesive on the inside. They are ideal for use in marine and automotive applications. Now you can solder and seal while waterproofing your wire joints at the same time! The exterior polyolefin tubing seals wires with amazing insulation & tensile strengthand is transparent so you can visually inspect the connection.