Feature
It is a Female Cigarette Lighter Socket to a 5.5mm x 2.1mm 12v DC.
Cigarette Lighter Socket DC 5.5mm x 2.1mm Cable, you can use your Car Charger,UPS Battery Backup and Portable Generator to power electronics or vehicle-mounted devices powered by 12v DC
One end of this adapter is a female socket connector like a car cigarette lighter socket in most vehicles. The other end is a 5.5mm x 2.1mm male barrel connector adapter
DC 5.5mm x 2.1mm - outer dimension 5.5mm, inner dimension 2.1mm.

Package
1 x  Female Cigarette Socket
or
1 x  Male Cigarette Socket