I use my phone pretty much all day long. YouTube, Tether, Texting, Facebook, Netflix, Games (FieldRunners 2 for Android - Plus many others), recording videos, taking pictures, and etc. It's a computer in your pocket. And NO MATTER HOW BIG your phones battery is, it's GOING to get low and you're going to scramble to find a charger. I can't tell you how many times I've had this charger in my pocket, CHARGING my phone! Yes, you can use a car charger, but say your phone is about to die and you can't leave your phone in your car or you'll miss an important call or text (or say your car doesn't charge your device while the key is not in the ignition - like mine...), you NEED to have your phone on you, but you know it's about to die. If you charge it on the way to the store, it's only going to get a few minute charge and then you pull it off and that only added a percentage or two to your almost dead battery. You can rest assure your phone is in your pocket (or purse, etc) .... CHARGING! So if it rings, you'll be able to answer it. This will more than top off your phones battery. If you're a person that uses wifi tether, that drains your battery FAST and this thing will provide you with security knowing that your phone can be recharged and used even longer, without being near a power source. If you find yourself with a phone that doesn't make it all day, you're a power user, or will be away from an outlet for a while... Save yourself time and money, and buy this thing!