With a ring of solder on the inside, these heat-shrink splices create secure, water-resistant connections between wires without the need for a crimping tool. Instead, heat the splice with a heat gun or butane torch to shrink the tubing, seal the connection, and liquefy the solder.

Because they use solder, these splices make more reliable connections than crimp-on splices. The melted solder fills the gaps between the wires' strands to make the electrical connection. Made of a tin-bismuth alloy, it's safe to use where lead is prohibited. It has a lower melting point than lead, so you're less likely to melt the heat-shrink tubing before melting the solder.

A layer of hot-melt adhesive lines the inside of the heat-shrink tubing to prevent the wires from pulling apart. The adhesive also seals the connection, blocking out water, dust, and other contaminants that can corrode the wire and cause a short.

To help with identification, each size has a different color. All are UL recognized for use with other components in an electrical system. When used with other UL recognized components, such as wires of the correct gauge, they can be part of a UL listed final product.