I bought this because I was going to a festival for a couple of days and man did it pay off. It holds its battery for quite a long time. I charged my phone to 100% battery and it only used 1 bar of battery. My brother and I could even charge our phones while it was also charging our portable speaker. The only downside about this power-bank is that it is SUPER HEAVY, but even then I would say it is worth it.