Replace your Garmin Dezl 770LM Battery or Keep an Extra Battery on hand as a backup. This is an Extended Capacity 1200 mAh, Lithium-Ion Battery that offers up even more up time than your original. Works in your Garmin Dezl 770LM GPS. Simple, Easy and Inexpensive! You get a New Battery, FREE Special Tools (necessary for installation), an Easy to Follow Installation Video, AND You also get a full ONE YEAR Money Back Guarantee exclusively when you purchase from us!