I purchased this from my local goodwill store for $6.88 it did NOT come with a cord, straight AC in. I noticed a small keyway at the bottom of the socket, I have an AC cord that fits,although the cord does not have a keyway and is smaller it fits either way, my concern is not having the proper cord,is the keyway there to prevent plugging it in the wrong way and is this polarized? I don't want to let the magic smoke out that makes things work LOL thanks in advance, and thank you for allowing me in the group.