Sometimes your phone's battery life won't cut the mustard. That's where USB powerbanks like this one from BioLite come in very handy. They store up to 20 watt hours, and can recharge your phone when an outlet isn't handy.
This particular BioLite model has a stainless steel casing, which makes it more durable than other plastic competitors. It can also handle unexpected rain or spills, which make it a great camping companion.
We've featured BioLite products before on the Reserve before like this kettle pot, and they're generally received as great products.