4 Port Double Set Screw Panelboard Lug 1000 MCM - 500 MCM Large size set screw connectors with multiple mounting holes for a secure, turn-prevent connection. Made of 6061T-6 aluminum alloy. Tin plated for low contact resistance. For use with copper or aluminum conductors. 600V (2000V max, per UL486B). UL 486A/B Listed. Temperature rating 90 degrees C. All hole spacing is NEMA standard of 1.75".