Rarely do you find a product that works better than the manufacturer claims. This is one of those times. I bought the Cellboost for my Samsung phone from a local drug store chain. My phone was not quite dead, but near there. The package claims to give you 60 hours of standyby time and 60 minutes of talk time on a 1 hour charge. To be quite honest, I haven't used 60 minutes. But, notice I said a 1 hour charge is all you are suppose to get. Well I charged it for one hour at work. I took it home and charged my phone with it for another hour. None to full charge. I woke up the next morning and popped this in again for approx. a half hour and my phone stated FULLY CHARGED. It doesn't stop there because I'm actually charging my phone with this device today (bought this 2 days ago) and the charging icon is on my phone. So, this device is definately a good item in an emergency. You may just get a full charge out of it. I recommend everyone buy at least one for an emergency. It claims to be good for 3 years (i.e. you can not touch it for 3 years and use it). I'm guessing the estimates are based on year 3, because right now its performing about 3 times better than they claim.