When you exercise, the Power Watch Series 2 Thermoelectric Activity Tracker makes full use of your excess body heat. So not only do you benefit from feeling the burn of your workout, but your smartwatch also gets some juice. Including the Series 2, Series 2 Premium, and Series 2 Luxe, these smart activity trackers will be on whenever you need them. The three models provide the same primary features, though they have different casing and strap materials. Because it uses your body heat and solar power to charge, you never have to plug this thermoelectric watch in. Monitoring your heart rate, GPS location, and sleep, this thermoelectric smartwatch can even withstand water up to 200 meters deep. It’s truly a rugged watch for the adventurous lover of the outdoors.