Fitbit, Inc. - Fitbit Introduces Fitbit Charge 4, its Most Advanced Health & Fitness Tracker with Built-in GPS, Active Zone Minutes, Spotify, Sleep Tools, Fitbit Pay and More
Fitbit Charge 4 Review: A Simple and Effective Fitness Tracker | WIRED
Fitbit Charge 4 review: Top fitness tracker with one problem
Fitbit Charge 4 vs. Fitbit Charge 3: What's the difference and should you upgrade? | iMore
Fitbit Charge 4 (NFC) Activity Fitness Tracker, Black - Walmart.com