12-10 to 8 gauge heat-shrink step-down butt splice terminals. For use in harsh environments, these terminals feature a heat shrink connection that also has an internal sealant. After crimping the terminal onto the wire, simply apply heat. Keeps moisture out while ensuring your wire does not pull out of the terminal. Connect two wires together. Insert wires on each end until they reach the built-in wire stop in the center. Two crimps are required, one for each wire, plus heat.