Garmin's Vivosmart 4 combines pulse-ox and a week of battery life for $129 | Ars Technica
vívofit Owner's Manual - Replacing the vívofit Device Batteries
Replacing the batteries in a Garmin Vivofit 4 - YouTube
Amazon.com: Garmin vívofit 4 activity tracker with 1+ year battery life and color display. Small/Medium, Black. 010-01847-00, 0.61 inches : Sports & Outdoors
5 Pack - Battery Replacement for Garmin Vivofit Jr Activity Tracker Watch Junior | eBay