[Big Cahuna]

It's called an SAE connector. It's used as an outlet for many different devices. I put one on every motorcycle I buy and use them mostly for trickle charging and running USB devices.

 

[Big Cahuna]

Thanks! So you essentially need two of these to connect to one another right? One end to battery and the other to the battery charger?

The device(s) will have an SAE plug on it, too.

By the way, you should go ahead and install it. You'll eventually want to plug something in it. When you realize what it is you will wonder how you survived without it.