For copper-to-copper connections. Bolt and nut made of high-strength, corrosion-resistant silicon bronze alloy. For making pigtail, tap or straight splice with larger conductors, solid or stranded. Split bolts slip over continuous wire. The end of the other wire is then placed over the continuous wire inside the unit and the nut is tightened. Connections must be completely insulated. UL (Underwriters Laboratories) listed