Living in Montana, we spend most of our free time skiing, cycling, and running. The iPhone has become part of our active gear, particularly for use as a gps. And on that 5 hour mountain bike ride or back country ski trip even the iPhone runs out of battery when using the gps. From my research there is no better option than the Mophie Juice Pack. It is sleek with a great design, and the extra juice is what we need.