I've been using an Anker 6400 mAh charger for a little over a year. It's small, light weight and charges my iPhone 6 about 1 1/2 times. I forget how much of a charge it will provide my iPad. Maybe 40-50% before it's dead. Overall it's a good product that you can put in your pocket and forget about. I recently ordered their "power house" charger. It's the Astro E7 25600 mAh. This thing is amazing!!! It will charge my iPad Air twice. Or I can lose track of how many times that I charge my phone. They say it can do it ten times. It's kind of big so your not going to forget that you have it in your pocket but it will provide plenty of power for you and your friends who can connect to one of the three ports. Plus it has a flashlight incase you need some light at night. I'll be keeping the 6400 around for light duty and use the 25600 when I need a lot more power.
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