Make quick, secure connections with their easy-on wing-type design providing positive continuity between conductors. The expandable square wire spring creates a strong vibration- connection. Their tough, shell shields against environmental extremes. The color-coded high dielectric shell features a deep skirt design to prevent exposure of bare wire while providing superior flash-over protection. Splices copper to copper. These connectors comply with Federal specification W-5-610d and are UL (Underwriter's Laboratories) 486C listed and CSA (Canadian Standards Association) certified. 600 volt.