I purchased a black "air" about 5 days ago. Previously I was using something called a "Mobile Power Station" ("MPS") which I purchased on ebay (search iphone battery case). This unit completely incased the iphone including the face (it has a plastic shield which covered the face). It worked great (2100 amh) and charged the phone almost twice from completely dead. Only problem - it was the size of a brick.
Purchased the "air" primarily because of the size. It fits nicely on the phone. It was the same height as the MPS even though the "air" claims to be the thinnest battery case but the Mophie is about .25 inch shorter and about .5 ounces lighter. Doesn't sound like much but it makes a world of difference in terms of how the phone looks and feels when in the case. The Mophie is well constructed, looks good and feels good in the hand without adding substantial weight.
As to how I carry the phone with the Mophie on (I keep it on all the time) I went down to Microcenter here in my home town of Columbus and bought a generic leather "pouch" type PDA case with a rotating belt clip. The phone just slides in the pouch and is held firmly in place by the elastic siding. It works and fits perfectly. The fit is snug enough that even if I turn the phone and holster completely upside down the phone stays in place. It is not too snug however to allow me to remove it easily from the pouch with firm pressure.
As to the performance of the Mophie this is what I have found. It's rated at 1200 amh which means it has about 90% of the capacity of the actual iphone battery. This is what I have found in real life use from a relatively heavy user. My day typically starts about 8:00. By 4:30 to 5 I get the 20% warning. I turn the "AIR" on to charge. I generally try not to use the phone when charging. In about an hour the "air" has charged the phone to about 90% and still indicates two lights worth of charge on the back of the case. I turn the Air off at which time I will use my phone again until it runs down to 20% again. By that time my day is usually done but I went ahead and turned the AIR on again to see how it would charge. It took it from 20% to about 60-65% before it was dead. So all together the Air took the battery from 20% to 90% and from 20% to 62.5% on one charge. Not bad for what I think most people need.
One other comment. I have had no problem with signal degradation or the micro USB port. The only problem I've seen is that you get two different readings with the blue led lights on the back depending on whether the air pack is on or off. It is not unusual for me to get 4 lights showing when the AIR is off and 2 lights showing when the AIR is on. The lights showing on the ON setting I believe are the most accurate.
Hope this helps
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