Replace your Garmin Forerunner 305 Battery or Keep an Extra Battery on hand as a backup. This is an 700 mAh Lithium Ion Battery that works in your Garmin Forerunner 305 GPS. Simple, Easy and Inexpensive! You get a New Battery, AND You also get a full ONE YEAR Money Back Guarantee exclusively when you purchase from us! Please note, this battery installation requires soldering.