It's a "mains charger". Means it's something you plug into the wall (no batteries).
But it will have a UK plug on it, so you will need to get a plug adaptor for it, should you need to use it in the US or elsewhere.
I found the exact same charger that Apple sell in their stores on eBay for like $5. Works well for me.
Originally Posted by Youngbinks
Is it battery powered or does it have a wall adapter?