The latest designed 3-prong /2-prong adapter is to transform Medium Screw Socket into a 2 prong or 3 prong outlet. It fits for regular base light bulbs, E26 Sockets. And the outlets are polarized, one slot is longer than another. The outlet adaptor is not water resistant. If you want to use in outside to give extra outlets for cord Christmas string light or device with AC plug ,keep the outlet adapter covered/dry (like on a covered front porch in porch light socket, covered floodlight socket ,ect). This adapter not only works with two pronged devices but also three pronged appliances adaptable.(Only for adapting 3-prong plug ,not turly grounded.) Specs: Max Wattage / Voltage for outlets: 660W / 125V ( Recommended the amperage of all your combined devices is less than 5 amps )