Since Japan has one of the highest penetration rates when it comes to cellphones, it makes perfect sense for phone owners to carry around the Echo Charge 1100. This device is a portable backup battery that can be charged via a power outlet before use, whereby you can easily plug it into your handset whenever it flashes the “Low Battery” warning. As its name suggests, the battery has a powerful 110mAH capacity to keep you talking long after your phone’s battery would have exhausted itself. Measuring a mere 11mm in thickness and weighing 50 grams, packing in the Echo Charge 1100 is pretty much hassle-free during your travels. It retails for just a shade under $30 after conversion.