Replace your Garmin Forerunner S1 Battery or Keep an Extra Battery on hand as a backup. This is an 200 mAh Lithium Ion Battery that works in your Garmin Forerunner S1 Smartwatch. Simple, Easy and Inexpensive! You get a New Battery, Special Installation Tools, AND You also get a full ONE YEAR Money Back Guarantee exclusively when you purchase from us! Video coming soon.