I have a Ravpower 5200 mAh I carry all the time since my headlamp, GPS when I carry it, delorme, and phone all use rechargeable batteries and if I'm going on an extended trip I bring my Anker 10,000 mAh pack. Been doing this for the past 3 years for 40-50 days each. I personally don't understand the draw to the poseidon units that are expensive and bulky with a pointlessly long cord and the unit doesn't do anything mine above already do well. The one thing to pay attention to, and it's not as big of a deal now, as when I was looking to go rechargeable is the output jack and how much output it can handle. Some of the items we recharge require a high draw charge and some of the early battery packs couldn't push that much juice. Technology moves pretty fast so I don't think that is as much of a concern now.