Smartphone batteries usually go down fast because of heavy use. My phones batteries seem to be low all of the time when I am out and about. I got this on amazon http://www.amazon.com/dp/B0186E7XQA I usually am on social media, taking pictures and more so I needed a portable charger and got this. This is thin just as the description mentions. I was able to charge my phone up to 100% with this. My phone was at 76% and it charged it up to 100% in less than an hour. What is unique about this portable cellphone charger is how it has four blue lights on the front of it that shows how much it is charged up to and when you pick it up the lights come on. This comes with and adapter on the inside of it for an iphone device. I had a little struggle with getting it out but I had finally used the charger cord to wiggle it out. I have been keeping this in my purse and it does not take up much room at all. I was able to recharge this on my laptop. I did not have any problems with this cellphone charger and I would recommend it. I received this product for free in exchange for my honest and unbiased review.