This is an ONN DS car charger, model ONA12MGH021.
This black charger plugs into the cigarette lighter slot of your car and charges your Nintendo DS gaming system. This cable has an input of DC10.8V-30V, 0.6A, and an output of DC5V, 1.2A.
This charger is in good pre-owned condition. It hasn't been tested and is being sold as-is.