This PowerZone adapter can connect a 3-conductor grounded plug to a 2-conductor polarized receptacle. This adapter also has a built-in power indicator light that shows the outlet is "on". The adapter is very useful in older homes where there are only 2-prong receptacles and you need to power a 3-prong grounded appliance. Each 3-to-2 adapter has a grounding ring that will secure to the screw that holds the faceplate to the wall outlet so installation is simple and safe.