The WMC 3/2 – Wonder Mains Combo 3/2, is a high quality Mains Power Surge Protector device with a 3 prong and a 2 prong plug that guards equipment and appliances on any electrical mains line with proprietary designed circuitry that performs a health check of the socket it is plugged into for correct grounding (earthing), which is an important requirement for effective surge protection.