I think some changes to the design of this bag would be appreciated. Maybe it's too small - maybe an inch or two in all dimensions would be great. Probably intended for small children, in which case it would be ideal. One of the additions would be the presence of a dedicated battery case and cable extensions that would also serve to replace the battery inside. It would be very ideal - both battery powered for devices and a connector to charge the battery without taking it out of your pocket. The second charging port should be on the strap. I think these changes will double the cost and I will buy this improved bag immediately. Update: The supplied US extension cord is of very poor quality. It doesn't work half the time (which is bad because it likely means a weak or intermittent connection), which can be dangerous for both your devices and the battery you're using. It is best to run the power cable(s) of your choice through the side connection without an extension cable.