Fitbit has confirmed that “a small number of users” are having problems with the band on their Fitbit Charge 4 – and it’s taking action.

The Fitbit Charge 4, which launched earlier this year, has a very similar design to its predecessor, and the standard version features a silicone band that attaches seamlessly to the case. Unfortunately, some owners have noticed that the two parts don’t connect as neatly as they should, leaving a gap.
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https://www.techradar.com/news/having-problems-with-your-fitbit-charge-4s-band-help-is-at-hand