Electrical Plug Lock I Was Wondering If There Is Such Thing As An Electrical Plug In That Is Powered By Batteries?

I was wondering if there is such thing as an electrical plug in that is powered by batteries? - electrical plug lock

I always go to a flea market and having the good will and always have elements I like to buy but can not connect, so I wondered if anyone knows whether to take such a thing and hand in a position to point to get in touch to see if they work? the batteries? Goodwill to make plug-ins, but a ban on the use of cutomers baracaded as disabled or locked.