I have this device which I got from a similar Newegg deal. Charges my iPhone 5s multiple full charges. It's a little big/heavy to carry around in a pocket, though only slightly so, so you can certainly carry around if you want particularly in a jacket pocket. Great for travel. I always throw it in my carry-on when I'm traveling now and don't worry about keeping my phone charged even on long trips.
I have two of these external batteries. I love them. I carry one around in my messenger bag; I would not recommend putting in your pants pocket. I did try putting it in my winter jacket but it makes the jacket considerably heavier.
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I dig around and see Newegg sell the 20Ah for $20. Why are you guys willing to pay more for less? Maybe brand? I've never heard of RAVPower. What matter is what battery cells they use inside and nobody state what they use inside.