Top-of-the-Line Industrial Quality Heavy Gauge Copper Alloy One-Piece Arm for Top Performance Large Silver Cadmium-Oxide Contacts for Long Life, Prevent Sticking, Welding and Excessive Pitting Fully Enclosed Switch Mechanism in Rugged Housing for Strength, Track and Arc Resistance Brass Combination-Head Terminal Screws on Extra Heavy-Duty Devices, Steel Combination Head Terminal Screws on Other Devices