ROLLDOCK lightning mobile battery dock 3,000 mAh. A charging dock that can also be used as a mobile battery. Its design makes it possible to use it as a mobile battery, an item that is so easily forgotten when going out. When at home, it functions as a dock that offers a perfect angle for iPhone use. When going out, just wrap the cable up to transform it into a portable mobile battery. You’ll never forget your iPhone charger again.