This is the JuiceBuddy. It’s a tiny, pocket-sized charger with fold-in prongs that make it ultra-portable. It can be attached to a keychain so that you always have it on-hand.
There are few things more annoying than having a dying battery and realizing that you forgot your charger. Sometimes, you can plug into your laptop, and that works, but most of us don’t always have the charger on-hand, and carrying an extra cable is usually easy if you have more than one iOS device (those iOS device USB cables tend to pile up by your third iPhone).
It’s worth checking out.