I recently purchased this battery pack RP-PB22 as a backup power supply for traveling especially when I go camping or backpacking where I have no access to an external power source. While the device is a tad heavy for backpacking at 10.8 oz. it works incredibly well charging 2 devices via iSmart ports simultaneously with a max output of 4.5 A while automatically detecting the charging current maximizing charging speed and has a built in short-circuit and over-charge protection which turns the device off when fully charged. The design is sturdy and elegant and also has a built in flashlight and comes with a cool travel pouch and 2 USB to Micro-USB charging cables. So far I have been very impressed with it's performance which exceeds other charging external battery packs I've purchase.