For 220V relays, they are designated for single-phase AC systems for 220-240V/50Hz Electricity in Europe and Asia. These relays have heavy-duty contacts that are composed of copper-silver alloy with a rating of 10-20 Amps. This makes them ideal for lights, HVAC systems, and small motor control. Many models include built-in surge arresters to handle voltage transients up to 4kV. They also use flame-retardant materials (UL 94 V-0) preserving voltage while meeting IEC 60664-1 insulation which makes them ideal for overload fuse protection.